Peptide enzyme inhibitors

ABSTRACT

WHEREIN Y IS LYS OR GLU, 11. AN UNDECAPEPTIDE OF THE FORMULA   PGLU-TRP-PRO-ARG-PRO-V-PRO-W-ILE-PRO-PRO   WHEREIN V IS THR OR GLY AND W IS GLN OR GLU, 12 A. TRIDECAPEPTIDE OF THE FORMULA PGLU-TRP-PRO-NLE-T-PRO-PRO   WHEREIN T IS AS DEFINED ABOVE,   PGLU-TRP-PRO-ARG-PRO-GLU-PHE-PRO-PRO, PGLU-TRP-PRO-ARG-PRO-LYS-PHE-ALA-PRO, PGLU-TRP-PRO-D-ARG-PRO-GLN-ILLE-PRO-PRO, PGLU-TRP-PRO-AGR-PRO-GLN-PHE-PRO-PRO, PGLU-TRP-PRO-GLY-PRO-GLU-ILE-PRO-PRO, PGLU-LYS-PHE-ALA-PRO-GLN-ILE-PRO-PRO,   10. A DECAPEPTIDE OF THE FORMULA   PGLU-K-TRP-PRO-ARG-PRO-GLN-ILE-PRO-PRO   WHEREIN K, P AND Q ARE AS DEFINED ABOVE, PGLU-U-TRP-PRO-ARG-PRO-GLN-ILE-PRO-PRO   THE ENZYMATIC CONVERSION OF ANGIOSTENSIN I INTO ANTIOTENSIN II IS INHIBITED BY A PEPTIDE OR AN ACYLATED PEPTIDE HAVING ONE OF THE FOLLOWING AMINO ACID SEQUENCES:   1. AN ACYLATED TRIPEPTIDE OF THE FORMULA   CHC-PHE-ALA-PRO   WHEREIN CAC IS CHLOROACETIC ACID, 2. A TETRAPEPTIDE OF THE FORMULA   PGLU-TRP-ALA-PRO OR PGLU-LYS-TRP-PRO,   3. AN ACYLATED TETRAPEPTIDE OF THE FORMULA   DAC-FLY-ALA-PRO OR A-LYS-PHE-ALA-PRO   WHEREIN DAC IS DIAZOACETIC ACID, AND A IS CHLOROACETIC ACID, CYCLOBUTYLCARBOXYLIC ACID, CYCLOPENTYLCARBOXYLIC ACID OR CYCLOHEXYLCARBOXYLIC ACID, 4. A PENTAPEPTIDE OF THE FORMULA   PGLU-C-TRP-ALA-PRO   WHEREIN B IS LYS, NLE, GLU OR GIN,   PGLU-C-TRP-ALA-PRO   WHEREIN C IS NLE, HIS, ORN OR ARG, N&#39;&#39;PGLU-LYS-TRP-ALA-PRO,PGLU-LYS-E-ALA-PRO WHEREIN E IS HIS , ILE, PRO, SER OR 3-AMINO-4-PHENYL-BUTYRIC ACID,   PGLU-LYS-PHE-F-PRO   WHEREIN G IS ALA, ASP OR GLU,   PGLU-LYS-PHE-ALA-G       WHEREIN W IS AS DEFINED ABOVE.   WHEREIN G IS ALA, ASP OR GLU,   PGLU-LYS-TRP-H   WHEREIN H IS ILE-PRO, THR-PRO-ALA-GLY OR ALA-SAR,   PGLU-TRP-PRO-J-PRO   WHEREIN J IS HIS, LYS OR GLY, 5. AN ACYLATED PENTAPEPTIDE OF THE FORMULA   DAC-GLY-GLY-PHE-ALA-PRO   WHEREIN DAC IS DIAZOACETIC ACID, 6. A HEXAPEPTIDE OF THE FORMULA   PGLU-LYS-PHE-ALA-PRO-PRO, PGLU-K-TRP-PRO-ARG-PRO   WHEREIN K IS ASN, NLE OR SER,   PGLU-NLE-TRP-PRO-L-PRO   WHEREIN L IS HIS OR GLY,   PGLU-ASN-TRP-PRO-M-PRO   WHEREIN M IS LYS OR GLY, 7. AN OCTAPEPTIDE OF THE FORMULA   PGLU-ILE-PRO-PRO-LYS-PHE-ALA-PRO,   8. AN ACYLATED OCTAPEPTIDE OF THE FORMULA   N-O-PRO-ARG-PRO-GLN-ILE-PRO-PRO   WHEREIN N IS CYCLOBUTYLCARBOXYLIC ACID, CYCLOPENTYLCARBOXYLIC ACID OR CYCLOHEXYLCARBOXYLIC ACID AND O IS TRP, TYR,   -TYR(-BZL)-   PHE, GLY, LEU, OR D-TRP,   N-TRP-PRO-GLY-PRO-LYS-SHPHE-ALA-PRO   WHEREIN N IS AS DEFINED ABOVE AND SHPE IS 3-AMINO-4 PHENYLBUTYRIC ACID, 9. A NONAPEPTIDE OF THE FORMULA   PGLU-TRP-PRO-P-PRO-Q-ILE-PRO-PRO   WHEREIN P IS ARG, HIS, LYS OR GLY AND Q IS GLN OR ASN,   PGLU-TRP-PRO-R-PRO-S-T-ALA-PRO   WHEREIN R IS ARG OR ORN, S IS NLE OR GLN AND T IS ILE OR PHE,   PGLU-TRP-PRO-ORN-PRO-S-T-PRO-PRO   WHEREIN S AND T ARE AS DEFINED ABOVE,   PGLU-O-PRO-ARG-PRO-GLN-ILE-PRO-PRO   WHEREIN O IS AS DEFINED ABOVE, PGLU-GLY-GLY-TRP-PRO-ARG-PRO-GLY-PRO-W-ILEPRO-PRO

3,832,337 Patented Aug. 27, 1974 3,832,337, PEPTIDE ENZYME INHIBITORS Miguel A. Ondetti, North Brunswick, and Josip Pluscec, East Brunswick, N.J., assignors to E. R. Squibb & Sons, Inc., Princeton,'N.J.

No Drawing. Continuation-in-part. of applications Ser. No. 58,686, July 28, 1970 and Ser. No. 61,794, Aug. 6, 1970, which is acontinuation-in-part of application Ser. No. 20,860, Mar. 18, 1970, all now abandoned. This application June-1,- 1972, Ser. No. 258,714

Int. Cl. A61k 27/00; C07c 103/52 US. Cl. 260-112.5 13 Claims ABSTRACT OF THE DISCLOSURE The enzymatic conversion of angiostensin I into angiotensin II is inhibited by a peptide'or an acylated peptide having one of the following amino acid sequences:

tyric acid;

'pGlu-Lys-Phe-F-Pro wherein F is Gly, Pro or Lac;

- pGlu-Lys-Phe-Ala-G wherein G is Ala, -Asp or Glu;

.pGlu-Lys-TIrp-H wherein H isIle-Pro, Thr-Pro, .Ala- Gly or Ala-Sar;

. pGln-Trp Pro-l-Pro wherein J is His, Lys or Gly; p

5. An acylat'ed pentapeptide of the formula 'Dac GIy-GIy Phe Ala-Pro wherein Dac is diazoacetic acid;

6. A hexapeptide of theformula pGlu-Lys-Phe-ihla-Pr o-Pro; pGlu -K-Trp-Pro-Arg-Pro 1G I -A sn-Trp-P ro -M -Pro wherein M is Lys oi '7 i 7. An octapeptideoftlie' formula pGlu-Ile-Pro-Pro-Lys-Phe-Ala-Pro; 8. An acyl ited octapeptide of the formula N bT re-Arg-Prb-Gln ile Pro-Pro nited Patent 01 iice wherein N is cyclobutylcarboxylic acid, cyclopentylcarboxylic acid or cyclohexylcarboxylic acid and O is Trp, Tyr,

Phe, Gly, Leu, or D-Trp;

N-Trp-Pro-Gly-Pro-Lys-BHphe-Ala-Pro wherein N is as defined above and BHphe is 3-amino-4- phenylbutyric acid; 1

9. A nonapeptide of the formula pGlu-Trp-Pro-P-Pro-Q-Ile-Pro-Pro wherein P is Arg, His, Lys or Gly and Q is Gln or Asnj pGlu-Trp-Pro-R-Pro-S-T-Ala-Pro wherein R is Arg or Orn, S is Nle or Gln and T is Ile or Phe;

pGlu-Trp-ProOrn-Pro-S-T-Pro-Pro wherein S and T are as defined above;

pGlu-O-ProArg-Pro-Gln-Ile-Pro-Pro wherein O is as defined above;

pGlu-Trp-Pro-Arg-Pro-Nle-T-Pro-Pro wherein T is as defined above;

pGlu-Trp-Pro-Arg-Pro-Glu-Phe-Pro-Pro; pGlu-Trp-Pro-Arg-Pro-Lys-Phe-Ala-Pro; pGlu-Trp-Pro-D-Arg-Pro-Gln-Ile-Pro-Pro; pGlu-Trp-Pro-Arg-Pro-Gln-Phe-Pro-Pro; pGlu-Trp-Pro-Gly-Pro-Glu-Ile-Pro-Pro; pGlu-Lys-Phe-Ala-Pro-Gln-Ile-Pro-Pro; 10. A clecapeptide of the formula pGlu-K-Trp-Pro-P-Pro-Q-Ile-Pro-Pro wherein K, P and Q are as defined above;

pGlu-U-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro wherein U is Lys or Glu;

11. An undecapeptide of the formula pGlu-Trp-Pro-Arg-Pro-V-Pro-W-Ile-Pro-Pro wherein V is Thr or Gly and W is Gln or Glu;

12. A tridecapeptide of the formula pGln-Gly-Gly-Trp-Pro-Arg-Pro-Gly-Pro-W-Ile- ProPro' wherein W is as defined above.

RELATED APPLICATIONS This application is a continuation-in-part of copending applications Ser. No. 58,686 filed 28 July 1970 and Ser.

. No. 61,794 filed 6 At'lgxl970'both 'now abandoned. The

. angiotensin II serves to tension. Y

latter application in turn is a continuation-in-part of copending application'Ser. No. 20,860 filed 18 Mar. 1970',

now abandoned. .7 BACKGROUND 0,1: THE INVENTION The action of the enzyme renin on renin substrate, a. pseudoglobulin in blood plasma, produces a polypeptide angiotensin I, also known-as hypertensin I. The latter is converted by an enzyme to angiotensin II, also known as hypertensin II or angiotonin. Angiotensin II is an active pressor substance which is present in the plasma of individuals with essential hypertension in quantities sufiicient to maintain elevated blood pressure. Inhibition of the en zyme responsible for the conversion of angiotensin I to remove a cause of essential hypera r r 3 Y OBJECTS OF THE INVENTION DETAILED DESCRIPTION -Unless otherwise indicated in the following specification and claims, all amino acids are of the L-configuration.

In describing the peptides of the present invention, the following abbreviations will be used throughout the specification and claims: y r v Ala-alanine Arg-arginine D-Arg-D-arginine Asnasparag ine Asp-aspartic acid BHphe-3-amino-4-phenylbutyric Cac-chloroacetic acid Cbc-cyclobutylcarboxylic acid Chccyclohexylcarboxylic acid Cpc-cyclop1 opylcarboxylic acid Dac-diazoacetic acid Glnglutamine Glu-glutamic acid Glyglycine Hishistidine Ile-isoleucine Lac-lactic acid Leu--leucine Lys-lysine Nle-norleucine Orn-ornithine Phe-phenylalanine Pro-proline Pyr or pGlu-pyroglutamic acid Sar--sarcosine Ser-serine Thr-threonine Trp-tryptophane D-Trp-D-tryptophane Tyr-tyrosine.

The following peptides of the present invention have been found to be effective in inhibiting the enzymatic conversion of angiotensin I into angiotensin II:

Pyr-Lys-HisAla-Pro .1

Pyr-Lys-Ser-Ala-Pro Pyr-Lys-fiHphe-Ala-Pro Pyr-.Lys-Phe-Ala-Pro-Pro Pyr-Asn-Trp-Pro-Arg-Pro Pyr-Asn-Trp-Pro-Gly-Pro Pyr-Ilefrofre-Lys-fhe kladfro cbc-Trp-Pro-Arg' -Pro-Clln-ilPro Pro Cbe-Tyr-Pro-Arg-Pro-Gln-Ile-Pro-Pro ]l3z1 v r Cbc-Tyr Pro-Argfro Gin-Ile-lro-Pro Cbc-Phe-Pro-Arg-Prd-Gln-Ile-Pro-Pro Cbc-Gly Pro-Arg-Pro- Gln-lle-Pro-Pro cpc-lueu-Pro -irg-l rm Cpe-D-Trp Pro-Arg-Pro- Gl H i I Pro -Gly-Pro Gln-lle Pro-Bro,

. ,Arg-P-ro Thr-Pro-Gln-IleTPro-Pm,

, Trp-Pro-Gly-Pro-Gln-lle Pro-Pro,

, Arg-Pro-Gly-Pro-Gln-Ile-Pro-Pro,

Pro-Arg-Pro-Thr-Pro-Gln-Ile-Pro-Pro,

Pro-Arg-Bro-Gly-Pro-Gln-Ile-Pro-Pro, and

Trp-Pro-Arg-Pro-V-Pro-Gln-Ile-Pro-Pro-wherein V is as defined previously.

The compounds of the present invention are capable of inhibiting the enzymatic conversion of angiotensin I into angiotensin II when employed at a concentration of from about 0.05 to about 10 g./ml. or of inhibiting the hypertensive effect of angiotensin I when administered in a dosage level of from about 0.5 to about 10 mg./kg. For the latter purpose they may be administered parenterally by incorporating the appropriate dosage with a physiologically-acceptable carrier.

The compounds of the present invention may be used per se or in the form of their physiologically-acceptable peptide salts. Examples of such salts are acid-addition salts, such as, for example, hydrochloride, hydrobromide, acetate, and haloacetate such as trifiuoroacetate and dichloroacetate.

Certain of the compounds of the present invention absorb ultraviolet light in the right 2950-3150 A. As such they may be employed topically as sunscreen agents to protect the skin against exposure to sunlight. A suntan lotion or cream is obtained by incorporating one or more of the hereinafter mentioned UV absorbing compounds in the appropriate vehicle in which parts given are by weight:

Suntan Lotion Vehicle:

2.0 polyethylene glycol 1500 20.0 polyethylene glycol 400 0.1 menthol 40.0 denatured alcohol 0.25 perfume 2.0 diethylene glycol monostearate q.s. distilled or deionized water to make 100.0 Suntan Cream Vehicle:

1.5 stearic acid 6.0 isopropyl myristate 1.75 ozokerite 170 0.2 preservative 0.25 perfume 1.0 triethanolamine q.s. distilled or deionized water to make 100.0

Those compounds which absorb UV are listed below by number wherein the number refers to the foregoing listing of peptides of the present invention:

Various intermediates of the present invention are employed in protected form. While only certain protected forms have been specifically disclosed in accordance with the requirements of optimal results in specific synthesis, it is to be understood that other protecting groups may also be used in accordance with the skill of the art. The choice of amino protecting group will depend on various factors, e.g., the nature of the amino acid or peptide which is to be attached to the N-terminal group of the amino acid or peptide, the ease of removal of the protect- I ing group, reaction solvent, temperature, etc. Some commonly usedarr'iirio' protectinggr'oup's are the following:

. amine hydrochlorides the p-toluenesulfonyl group v the benzyloxycarbonyl (carbobenzoxy) group substituted benzyloxycarbonyl andother urethane protecting groups p the trifluoroacetyl group the phthalyl (or phthaloyl) group the diphenylmethyl (benzhydryl) and triphenylmethyl (trityl) groupsl 8. the formyl group 9. lactams 10. Schitf bases and enamines 11. the benzylsulfonyl group 12. tritylsulfenyl and arylsulfenyll Some specific protecting groups are" tert.-butyloxycarbonyl, o-nitrophenylsulfenyl, and tosyl. A more complete listing may be obtained by reference to standard works on peptide synthesis, e.g., Bodanszky et-"-al., Peptide Synthesis, Chapter 4, Interscience, 19 66, or Schroder et al., The Peptides, Vol. 1, pp. xxiii xxix, Academic Press, 1965. I i I Examples of suitable hydroxyl protecting groups are, for example, benzyl, t-butyl, and tetr'ahydropyranyl.

The C-terminal group may also. be protected. In the compounds of all three categories, other functional groups, e.g. hydroxyl and guanidino, as well as amino groups other than the N-terminal .amino and carboxyl groups other than the C-terminal carboxyl, may also be protected.

The choice of carboxyl protectin-gg'roup will depend on various factors, e.g., the nature of the peptide being synthesized, ease of removal of protecting group, reaction solvent, temperature, etc.

Some commonly used carboxyl protecting group are the following:

1. salt formation 2. lower alkyl ester 3. phenyl substituted lower alkyl esters, e.g., benzyl and benzhydryl esters l p-nitrobenzyl esters p-methoxybenzyl esters phthalimidomethyl esters tertiary butyl esters cyclopentyl esters methylthioethyl esters.

10. trimethylsilyl group 11. hydrazides Some specific carboxyl protecting groups are methyl, ethyl, propyl, tert.-butyl, and benzyl. A more complete listing may be obtained by reference to standard Works on peptide synthesis, e.g. Bodanszkyet al., supra, or Schroder et al., supra.

Examples of suitable guariidine protecting groups are, for example, nitro, tosyl, pnitrobenzyloxycarbonyl, adamantylcarbonyl, and protona'tion. A more complete listing of hydroxyl and guani'dineprotecting groups may be had by reference to standard works on peptide synthesis, for example, the previously mentioned Bodanszky et al. or Schroder et'algtexts.

The following examples illustrates the invention without, however, limiting the same thereto. -All temperatures given are in degrees Celsius. Unless otherwise indicated, all optical amino acids are of the L-co'nfiguration.

EXAMPLE 1 Pyr-Tyr-Pro-Arg-Pro-Gln-Ile Pro-Pro 1. Tyr-Pro-trifiuoroacetate.-Proline tert.-butyl ester (0.80 g.) and tert.-butyloxycarbonyl tyrosine 2,4,5-trichlorophenyl'ester (238 g.) are dissolved in a mixture of 20 ml. of dichloromethane and 1 ml. of dimethylformamide (DMF). After 24 hours, the reaction mixture" is diluted with dichloromethane, washed with aqueous acid 9 and base and the solvent evaporated in vacuo. The residue is dissolved in trifiuoroacetic acid. After one hour at room temperature the solvent is removed in vacuo. The residue is triturated with ether until solidification.

2. Pyr-Tyr-Pro.--T he above dipeptide (1.2 g.) and pyroglutamic acid 2,4,5-trichlorophenyl ester (1.1 g.) are dissolved in a mixture of 0.5 ml. of triethylarnine (TEA) and DMF (15 ml.). After 16 hours at room temperature, the solvent is removed in vacuo, the residue dissolved in isopropanol and the solution poured into diisopropyl ether with stirring. The solid precipitate is filtered and washed with isopropyl ether.

3. Z-Pro-Pro-OBu .Benzyloxycarbonyl L proline (69.72 g.) and proline tert.-butyl ester (49 g.) are dissolved in 560 ml. of dichloromethane (DCM) and the solution chilled in an ice-water bath for 10 minutes. Dicyclohexylcarbodiimide (57.68 g.) is added and the mixture stirred for 1 hour at and 4 hours at room temperature. The dicyclohexylurea is removed by filtration and the filtrate diluted with DCM (850 ml.) and washed twice with 20% citric acid, twice with water, twice with saturated sodium bicarbonate and twice with water. After drying over sodium sulfate, the solvent is removed in vacuo and the solid residue crystallized from 4 liters of hexane.

4. Z-Ile-Pro-Pro-OBu .-Benzyloxycarbonyl-L-prolyl-L- proline tert.-butyl ester (46.5 g.) is dissolved in a mixture of absolute ethanol (750 ml.) and N HCl (122 ml.) and hydrogenated over palladium on charcoal (8 g.) until no more carbon dioxide is evolved (4 hours). Thin layer chromatography is utilized to check for the complete removal of the protecting group. The catalyst is removed by filtration and the filtrate concentrated to dryness to constant weight (ca. 37 g.). This residue is dissolved in DMF (195 ml.) and the solution neutralized with TEA (17.1 ml.) while stirring and cooling in an ice-water bath. Immediately following this neutralization benzyloxycarbonyl L isoleucine N-hydroxysuccinimido ester (50.5 g., mp. 114-116) is added. The reaction is allowed to proceed overnight at room temperature (ninhydrin test becomes negative). Dimethylaminopropylamine (7.7 ml.) is added and after 2 more hours at room' temperature the excess basicity is neutralized with acetic acid. After concentration in vacuo to half volume, the reaction mixture is diluted with ethyl acetate (1.5 l.) and washed twice with citric acid, twice with water, twice with saturated sodium bicarbonate and three times with Water. The organic phase is dried over Na SO and the solvent removed in vacuo until constant weight.

5. Z-Gln-Ile-Pro-Pro-OBu.Benzyloxycarbonyl-L-isoleucyl-L-prolyl-L-proline tert.-butyl ester (58 g.) is dissolved in a mixture of absolute ethanol (1.2 1.) and N HCl (.116 ml.) and hydrogenated over 10% palladium on charcoal (10 g.) until no more carbon dioxide is evolved (5 1.). Completion of the deprotection is checked by thin layer chromatography. The catalyst is filtered off and the filtrate concentrated to dryness in vacuo (50.9 g.). This residue is dissolved in DMF (175 ml.) and the solution neutralized with TEA (16.2 ml.) while stirring and cooling in an ice-water bath. Immediately after neutralization, benzyloxycarbonyl-L-glutamine p-nitrophenyl ester (49.6 g.) is added and the reaction allowed to proceed overnight at room temperature (ninhydrin test becomes negative). Dimethylaminopropylamine (4.1 ml.) is added and after 2 hours the excess basicity is neutralized with acetic acid and the reaction mixture concentrated to onethird of the original volume in vacuo. Ethyl acetate (2.5 l.) is added and the solution thus obtained is washed twice with 20% citric acid, twice with water, about 15 times with 0.5 N NH OH (until the ammonium hydroxide solution is practically colorless) and five times with water. After drying over sodium sulfate, the solvent is removed in vacuo and the residue crystallized from ethyl acetate.

6. Z-ProGln-Ile-Pro-Pro-OBu.Benzyloxycarbonyl-L- glutaminyl-L-isoleucyl-L-prolyl-L-proline tert.-butyl ester 10 (50 g., 92 mmole) is dissolved in a mixture of absolute ethanol (1.2 l.) and N HCl (93 ml.) and hydrogenated as described previously. The tetrapeptide ester hydrochloride (58 g.) is dissolved in DMF (160 ml.) and the solution neutralized with TEA (13.0 ml.) while stirring and cooling in an ice-water bath. Immediately after neutralization benzyloxycarbonyl L proline hydroxysuccinimido ester (45 g., mp -91) is added and the reaction allowed to proceed overnight at room temperature (ninhydrin test becomes negative). Dimethylaminopropylamine (11.1 ml.) is added and after 2 hours the excess basicity is neutralized with acetic acid and the reaction mixture concentrated to /3 its original volume. Ethyl acetate (1.5 l.) is added and the solution is washed three times with 20% citric acid, twice with water, twice with saturated sodium bicarbonate, and three times with water. After drying over sodium sulfate, the solvent is evaporated in vacuo and the gelatinous residue dissolved in ethanol, concentrated to dryness again, redissolved in ethanol (75 ml.) and added slowly to 1.6 l. of ether with vigorous stirring. The stirring is continued for 20 minutes and the precipitate filtered and washed with ether. The product is obtained as a glassy powder after drying in a desiccator.

7. Z-Arg-Pro-Gln-Ile-Pro-Pro-OBu .-Benzyloxycarbonyl L prolyl L glutaminyl L isoleucyl L prolyl- L-proline tert.-butyl ester (17.76 g., 24 mmoles) is dissolved in a mixture of absolute ethanol (480 ml. and N HCl (26.4 ml.) and hydrogenated as described previously. The pentapeptide tert.-butyl ester hydrochloride (17 g.) is dissolved in DMF (36 ml.) and neutralized with TEA (3.84 ml.) while stirring and cooling in an ice-water bath. Immediately following the neutralization, benzyloxycarbonylnitro-L-arginine 2,4-dinitrophenyl ester (13.8 g.) is added and the reaction allowed to proceed at room temperature. After 1 hour TEA (2 ml.) is added and the reaction stored at room temperature overnight. Dimethylaminopropylamine (2 ml.) is added and after one hour the reaction mixture is concentrated to /3 of its original volume, diluted with ethyl acetate (1200 ml.) and washed twice with 20% citric acid, once with water, ten times with ammonia (400 ml. each, not all the yellow color disappears), and three times with water. After drying with sodium sulfate, the ethyl acetate is removed in vacuo to a heavy oil that solidifies upon trituration with ether (500 ml.). The solid is filtered, washed with ether and dried.

8. Arg-Pro-Gln-Ile-Pro-Pro- 2HCl.- Benzyloxycarbonylnitro L arginyl L-prolylL-glutaminyl-L-isoleucyl-L- prolyl-Lproline tert.-butyl ester (21.4 g.) is dissolved in trifluoroacetic acid (150 ml.) and the solution kept at room temperature for one hour. The solution is concentrated to 30 ml. in vacuo and 1 liter of ether added. The precipitate is filtered, washed with ether and dried in vacuo. This protected hexapeptide acid (20.3 g.) is dissolved in a mixture of methanol (800 ml.), water (400 ml.) and N HCl (46 ml.) and hydrogenated with 10% palladium on charcoal (4 g.) for 20 hours. The completion of hydrogenolysis is ascertained by the disappearance of the UV absorption at 270 m The catalyst is removed by filtration and the filtrate concentrated in vacuo. The residue is dissolved in methanol (70 ml.) and added to ether 1.5 1.) with vigorous stirring. The precipitate is filtered and washed with ether.

9. Pyr-Tyr-Pro-Arg-Pro-Gin-Ile-Pro-Pro.The tripeptide, Pyr-Tyr-Pro (23.3 mmoles) is dissolved in DMF (85 ml.) and 3.27 ml. (23.3 mmoles) TEA, the solution cooled to 20 (inside the flask, or -35 to 40 in the cooling bath) and kept at this temperature for 15-20 minutes. To this cold solution 3.19 ml. of isobutyloxycarbonyl chloride is added and then a time of 30 minutes is allowed for the mixed anhydride to be formed at the same temperature. A solution of Arg-Pro-Gln-Ile-Pro-Pro (16.5 g.) in DMF ml.) is precooled to about 0 and then added 1 1 into the solution of the mixed anhydride. At this moment, the pH value is adjusted to 8 with TEA 8.5 ml.) while the temperature of is maintained. After 20 to 24 hours at room temperature, the volume of the solvents is reduced to /3-% and poured into 20-25 volumes of EtOAc containing 3% of AcOH. The precipitate is washed thoroughly with EtOAc and then dried in vacuo over KO-H overnight.

EXAMPLE 2 Cpc-Phe-Pro-Arg-Pro-Gln-Ile-Pro-Pro 1. Z-Phe-Pro-OB.Following the procedure of paragraph 3 of Example 1, but substituting benzyloxycarbonyl- L-phenylalanine (0.28 mole) for benZyloxycarbonyl-L- proline, the foregoing dipeptide is obtained.

2. Cpc-Phe-Pro.-The dipeptide of the preceding paragraph (9.0 g.) is hydrogenated as described in paragraph 4 of Example 1, and the resulting dipeptide hydrochloride (7.1 g.) is allowed to react with cyclopentane carboxylic acid (2.3 g.), dicyclohexylcarbodiimide (4.1 g.) and TEA (2.8 mmole). The product is isolated as described in paragraph 3 of Example 1. The tertiary butyl ester is hydrolyzed by treatment with trifluoroacetic acid as described in paragraph 8 of Example 1.

3. Cpc-Phe-Pro-Arg-Pro-Gln-Ile-Pro-Pro. The nonapeptide is obtained by coupling the tripeptide of paragraph 2 to the hexapeptide prepared as described in paragraph 8 of Example 1 following the procedure of paragraph 9 of Example 1.

EXAMPLE 3 Cpc-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro 1. Trp-Pro-trifiuoroacetate.-Following the procedure of paragraph 1 of Example 1 but substituting tert.-butyloxycarbonyl tryptophane 2,4,5-trichlorophenyl ester (2.62 g.) for tert.-butyloxycarbonyl tyrosine 2,4,5-trichlorophenyl ester, the foregoing dipeptide is obtained.

2. Cpc-Trp-Pr0.The dipeptide of the preceding paragraph (1.32 g.) and cyclopentane carboxylic acid hydroxysuccinimido ester are dissolved in a mixture of TEA (0.5 ml.) and DMF (15 ml.). After 16 hours at room temperature, the solvent is removed in vacuo, the residue dissolved in isopropanol and the solution poured into diisopropyl ether with stirring. The solid precipitate is filtered and Washed with isopropyl ether.

3. Cpc-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro.The tripeptide from the preceding paragraph (9.3 g.) is dissolved in DMF (85 ml.) and 3.27 ml. TEA. The solution is cooled to -20 inside the flask, or -35 to 40 in the cooling bath, and kept at this temperature for 15-20 minutes. To the cold solution is added 3.19 ml. of isobutyloxycarbonyl chloride and 30 minutes are allowed for the mixed anhydride to form at this temperature. A solution of the hexapeptide (16.5 g.) in DMF (100 ml.) prepared as described in paragraph 8 of Example 1 which has been precooled to about 0 C. is then added to the solution of the mixed anhydride. At this moment the pH value is adjusted to 8 with TEA (8.5 ml.) while the temperature of 0 is maintained. After 22 hours at room temperature, the volume of 'the'solvents is reduced to about 4 andpoured into 20 volumes of EtOAc containing 3% of AcOI-I. The precipitate is washed thoroughly with EtOAc and then dried in vacuo over KOH overnight.

EXAMPLE 4 "Pyr-Tyr-Pro-Arg-Pro-Gln-Ile-Pro-Pro Bzl v 1. Tyr-Pro-trifiuoroacetate.Following the procedure of paragraph 1 of Example 1 but substituting tert.-butyloxycarbonyl- O-benzyl tyrosine 2,4,5-trichlorophenyl ester (2.86 g.) for tert. butyloxycarbonyl tyrosine 2,4,5-trichlorophenyl ester, the foregoing dipeptide is obtained.

2. Pyr-Tyr-Pro.The depeptide of the preceding paragraph (1.95 g.) and pyroglutamic acid 2,4,5-trichl0rophenyl ester (1.1 g.) are coupled to yield the foregoing tripeptide following the procedure of paragraph 2 of Example 3.

1 3. Pyr-Tyr-Pro-Arg-Pro-Gln-Ile-Pro-Pro.The foregoing nonapeptide is prepared by coupling according to the procedure of paragraph 3 of Example 3 ,the tripeptide of paragraph 2 with the hexapeptide prepared as described in paragraph 8 of Example 1. i

EXAMPLE 5 B21 1 Cpc-Tyr-Pro-Arg-Pro-Gln-Ile-Pro- Pro Bzl 1 1. Cpc-Tyr-Pro.The foregoing tripeptide is prepared by coupling the dipeptide (3.5 g.) prepared as described in paragraph 1 of Example 4 with cyclopentanecarboxylic acid N-hydroxysuccinimido ester (2.3 g.) following the procedure of paragraph 2 of Example 2.

2. Cpc-Tyr-Pro-Arg-Pro-Gln-Ile-Pro-Pro.-The foregoing nonapeptide is prepared by coupling according to the procedure of paragraph 3 of Example 3 the tripeptide (12.1 g.) of paragraph 1 with the hexapeptide (16.5 g.) prepared as described in paragraph 8 of Example 1.

EXAMPLE 6 Cpc-TyrwPro-Arg-Pro-'Gln-Ile-Pro-Pro The nonapeptide of Example 5 (500 mg.) is dissolved in a mixture of ethanol-water (9:1; ml.) and hydrogenated over 10% Pd on charcoal for 5 hours. The catalyst is filtered off and the filtrate concentrated to dryness in vacuo. The residue is dissolved in water and freezedried.

EXAMPLE 7 Cac-Phe-Ala-Pro The title compound is prepared according to the following series of reactions starting with 5 g of tert.-butyloxycarbonyl-proline polystyrene divinylbenzene copolymer resin containing 0.5 mmoles of proline per gram of resin:

1) Wash four times with dichloromethane (50 ml. each wash), four times with ethanol (50 ml. each wash), and four times with acetic acid (50 ml. each wash).

(2) Wash once with 1 N HCl in acetic acid (50 ml.) for 5 minutes, and wash again for 25 minutes (50 ml.).

(3) Wash four times with acetic acid (50 ml.- each wash), four times with absolute ethanol (50 ml. each wash), and four times with chloroform (50 ml. each wash). I

(4) Wash twice with 50 m1. of a mixture containing 3.2 ml. of triethylamine in 50 ml. of chloroform.

(5) Wash four timeswith chloroform (50 ml. each wash) and four times with dichloromethane (50 ml. each wash). I

(6) Couple with tert.-butyloxycarbonyl alanine (7.5 mmoles) and dicyclohexylcarbodiimide (7.5 mmoles) in dichloromethane (39 ml.). Alternately, a mixture of dichloromethane and dimethylformamide (2:1) may be used.

7) Repeat steps l-6, inclusive, but employin g tert; butyloxycarbonyl phenylalanine (7.5 mmoles) in step 6.

(8) Repeat steps 16, inclusive, but employing chloroacetic acid (7.5 mmoles) in step 6. I

(9) The Cac-Phe-Ala-Pro resin is suspended in trifluoroacetic acid (65 ml.) and hydrogen bromide is bubbled through for 30 minutes. The resin is filtered off and the filtrate is concentrated to'dryness in vacuaThe 7. ,13' residue is triturated with ether and the solid precipitate formed is filtered, washed with ether and dried.

EXAMPLE 8 Pyr-Trp-Ala-Pro .Starting with 1.0 g. of tert.-butyloxycarbonyl-proline polystyrene resin containing 0.2 mmoles of proline per gram of resin and following the procedure of Example 7, except that after the introduction of the tryptophyl residue, the wash solution in step 2 contains 40.4 ml. acetic acid, 9.1 ml. anisole, and 0.5 ml. mercaptoethanol, the following amino acids are introduced stepwise: alanine, tryptophane, and pyroglutamic acid. The tert.-butyloxy carbonyl group is used for protection of the N-terminal amino groups except for Pyr. To remove the tetrapeptide, the resin is suspended in a mixture of trifiuoroacetic acid (13 ml.), mercaptoethanol (2.8 ml.) and anisole (0.13 ml.); chilled in an ice-water bath; and HBr is bubbled through for 30 minutes.

EXAMPLE 9 Pyr-Lys-Trp-Ala 'The title compound is prepared following the procedure of Example 8 starting with tert.-butyloxycarbonylalanine polystyrene resin, but introducing the following amino acids stepwise: tryptophane, lysine and pyroglutamic acid.

EXAMPLE 10 Pyr-Trp-Pro-Arg-Pro-Lys-Phe-Ala-Pro EXAMPLE 1 l Pyr-Nle-Phc-Ala-Pro The title compound is prepared by the procedure de scribed in Example 7 utilizing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr.

EXAMPLE 12 Pyr-Gln-Phe-Ala-Pro The title compound is prepared as described in Example 7 employing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr. In the case of glutamine, the p-nitrophenyl ester is used instead of the dicyclohexyl-carbodiimide procedure.

EXAMPLE 13 Pyr-Glu-Phe-Ala-Pro "Thetitle compound is prepared as described in Example 7 employing the tert.-butyloxycarbonyl derivatives of the corresponding'amino acids, except for Pyr.

V EXAMPLE 14 Pyr-Lys-Ile-Ala-Pro .7 The title compound is prepared as described in Example 7 employing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr.

14 EXAMPLE 1s Pyr-Lys-Pro-Ala-Pro The title compound is prepared as described in Example 7 employing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr.

'EXAMP-LE 16 Pyr-Lys-Ser-Ala-Pro The title compound is prepared as described in Example 7 employing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr.

EXAMPLE 17 Pyr-Lys-Phe-Gly-Pro The title compound is prepared as described in Example 7 employing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr.

EXAMPLE 18 Pyr-Lys-Phe-Pro-Pro The title compound is prepared as described in Example 7 employing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr.

EXAMPLE 19 Pyr-Lys-Phe-Lac-Pro The title compound is prepared as described in Example 7 employing the tert.-butyloxycarbonyl derivatives of Phe-Lac, e-Z-Lys, and pyroglutamic acid without protecting group.

EXAMPLE 20 Pyr-Lys-Phe-Ala-Asp The title compound is prepared starting from tert.- butyloxycarbonyl-O-benzyl-aspartylpolystyrene resin (0.5 mmole/ g.) following the procedure described in Example 7 and employing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr.

EXAMPLE 21 Pyr-Lys-Phe-Ala-Glu The title compound is prepared starting with tert.-butyloxycarbonyl O-benzyl-L-glutamyl-polystyrene resin following the procedure described in Example 7 and utilizing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr.

EXAMPLE 22 Cac-Lys-Phe-Ala-Pro The title compound is prepared by the procedure described in Example 7 utilizing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr, and chloroacetic acid.

EXAMPLE 23 Dac-Gly-Phe-Ala-Pro 1. Boc-Ala-Pro-OBzl.Proline benzyl ester hydrochloride (20.5 g.) is dissolved in dimethylformamide (425 ml.). The solution is cooled to 0 C. and TEA (12.4 ml.) and tert.-butyloxycarbonyl-alanine p-nitrophenyl ester (25 g.) are added. After 21 hours at room temperature, the solvent is removed in vacuo and the residue dissolved in ethyl acetate and washed With 20% aqueous citric acid, water, saturated solium bicarbonate and water. The organic phase is dried over sodium sulfate and the solvent removed in vacuo. The residue is dissolved in ether and the product precipitated by addition of hexane.

. 2. Z-Phe-Ala-Pro-OBzl.The protected dipeptide of paragraph 1 is treated with trifluoroacetic acid and the resulting dipeptide benzyl ester (8.7 g.) is dissolved in a mixture of dimethylformamide ml.), TEA (3.19 ml.) and benzyloxycarbonyl-phenylalanine-p-nitrophenyl 15 ester (10.4 g.). After 18 hours, the reaction mixture is worked up as described in paragraph 1.

3. Phe-Ala-Pro.-The protected tripeptide of paragraph 2 (9.9 g.) is suspended in a mixture of methanol (225 ml.), water (25 ml.) and acetic acid (10 ml.). After addition of 10% palladium on charcoal (2.5 g.) the mixture is hydrogenated at normal pressure and room temperature for five hours. The catalyst is filtered off, the filtrate concentrated to dryness in vacuo and the residue purified from isopropanol-isopropyl ether.

4. Dac-Gly-Phe-Ala-Pro.-The tripeptide of paragraph 3 (420 mg.) is dissolved in a mixture of dimethylformamido (5 ml.), TEA (0.15 ml.) and diazocetylglycinep-nitrophenyl ester (316 mg). After 18 hours at 5 C., the solution is poured with stirring into isopropyl ester (100 ml.) and the precipitate filtered and washed with ethyl acetate.

EXAMPLE 24 Dac-Gly-Gly-Phe-Ala-Pro 1. Boc-Gly-Phe-Ala-Pro.The tripeptide of paragraph 3 of Example 23 (1.2 g.) is dissolved in a mixture of DMF (15 ml.), TEA (0.5 ml.) and tert.butyloxycarbonyl-glycyl-p-nitrophenyl ester. After 15 hours at room temperature, the reaction mixture is worked up as described in paragraph 1 of Example 23.

2. Dac-Gly-Gly-Phe-Ala-Pro-The partially protected tetrapedtide of paragraph 1 is treated with trifluoroacetic acid as described in paragraph 2 of Example 23. Glycylphenylalanyl-alanyl-proline trifluoroacetic is allowed to react with diazoacetylglycine-p-nitrophenyl ester as described in paragraph 4 of Example 23.

EXAMPLE 25 Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Ala-Pro The title compound is prepared by the procedure described in Example 7 utilizing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr. In the case of plutamine the. p-nitrophenyl ester is used for the coupling step.

EXAMPLE 26 Pyr-Trp-Pro-D-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared as described in Example 7 utilizing the tert.-butoyloxycarbonyl derivatives of the corresponding amino acids, except for Pyr. In the case of glutamine the p-nitrophenyl ester is used for the coupling step.

EXAMPLE 27 Cpc-Lys-Phe-Ala-Pro 1. Boc-Phe-Ala-Pro-OBzl.--The protected peptide prepared as described in paragraph 1 of Example 23 (20 g.) is dissolved in cold trifluoroacetic acid (200 ml.). After 20 minutes at room temperature most of the trifiuoroacetic acid is removed in vacuo. The oily residue is solidified by trituration with ether. This dipeptide ester trifluoroacetate is dissolved in a mixture of DMF (250 ml.), TEA (7.35 ml.) and tert. butyloxycarbonyl phenylalanine p-nitrophenyl ester (22 g.) After 24 hours at room temperature, the reaction mixture is worked up as described in Example 23. Y

2. Z-isys-Phe-Ala-Pro-oBzl.The protected tripeptide of paragraph 1 is treated with trifluoroacetic acid and the resulting tripeptide benzyl trifluoroacetate (10.2 g.) is dissolved in a mixture of dimethoxyethane (110 ml.), TEA (2.71 ml.) and N"-benzyloxycarbonyl-N -tert.-butyloxycarbonyl-lysine-N-hydroxy-succinimide ester g.). After 22 hours at room temperature, the. solvent is removed in vacuo and the residue triturated with cold water ml.), filtered and the'protected tetrapeptideester crystallized from absolute ethanol.

Boc

4. Cpc Lys Phe Ala-Pro.T he partially protected tetrapeptide (621 mg.) of paragraph 3 is dissolved in a mixture of dimethylformamide (5 ml.), triethylamine (0.15 ml.) and cyclopentanecarboxylic-acid N-hydroxy-- succinimide ester (253 mg.). After three hours the reaction mixture is poured into 3% aqueousacetic acid at 0 C. and the product filtered off.

5. Cpc Lys Phe-Ala-Pro. --The partically protected peptide (400 mg.) of paragraph 4 is treated with cold trifiuoroacetic acid (3 ml.). After 15 minutes at room temperature most of the trifluoroacetic acid is removed in vacuo. The oily residue is solidified bytrituration with ether. The tetrapeptide trifluoroacetate is purified by column chromatography (DE-52 Cellulose) using 0.005 M and 0.1 M ammonium acetate as a linear gradient.

EXAMPLE 28 Chc-Lys-Phe-Ala-Pro 1. Z-Phe-Ala-Pro-OBzL-The protected dipeptide prepared as described in paragraph 1 of Example 23 is treated with trifluoroacetic acid and the resulting dipeptide benzyl ester (8.7 g.) dissolved in a mixture of DMF ml.), TEA (3.19 ml.) and benzyloxycarbonyl-phenylalanine-pnitrophenyl ester (10.4 g.). After 18 ho'ursthe reaction mixture is worked up Example 23.

2. Phe-Ala-Pro.Th e protected tripeptide of'paragraph 1 (9.9 g.) is suspended in a mixture or methanol (225 ml.), water (25 ml.) and acetic acid (10 ml.). 'After addition of 10% palladium on charcoal (2.5 "g.)ythe mixture is hydrogenated at normal pressure and room temperature for five hours. The catalyst is filtered 01f, the filtrate concentrated to dyness in vacuo, and the residue purified from isopropanol-isopropyl ether.

3. Boc- Lys-Phe-Ala-Pro.The tripeptide of paragraph 2 (1.7 g.) is dissolved in a mixture of dimethoxyethane, (25 ml.), DMF (5 ml.),TEA (0;6 ml.) and N-tert.- butyloxycarbonylN -benzylox ycarbonyl lysine p-nitrophenyl ester 2.5 g.). After 17 liours at room temperature, the reaction mixture is worked .up'as described in paragraph 1 of Example 23. r

4. Chc-isys-Phe-Ala-Pro.?The.,)protected peptide. of paragraph 3 is treated with trifluoroacetic acid and the partially protected tetrapeptide'trifluoroacetate (1.4 g.) is dissolved in a mixture of dimethylformamide (10 ml.), tri ethylamine (0.28 ml.) and cyclohxane-carboxylic acid N- hydroxysnccinimido ester (800 mg.). After 18 hours at room temperature, the reaction mixtureis worked up asdescribed in paragraph 2of-Example 3. i w

5. Chc-Lys-Phe-Ala-Pro.--The partially protected tetrapeptide of paragraph 4 (900 mg.) treated with a 3.4 N solution of hydrogen bromide in glacial actic acid (10 ml.). After 20 minutes at room temperature, the solution is poured into ether (250 ml.)."Th'e product is-purifi'ed by column chromatography:

as described in paragraph I of 1 7 EXAMPLE 29 Cbc-Lys-Phe-Ala Pro Z 1. Boc-Lys-Phe-Ala-Pro.The tripeptide prepared according to paragraph 3 of Example 23 (3.2 g.) is dissolved in a mixture of dimethoxyethane (25 ml.), dimethylformamide (5 ml.), triethylamine (0.6 ml.) and N-tert.-butyloxycarbonyl-N -benzyloxycarbonyl' lysinep-nitrophenyl ester (2.5 g.). After 17 hours at room temperature, the reaction mixture is worked up as described in paragraph 1 of Example 23.

EXAMPLE 30 Pyr-Trp-lro-Arg-Pro The title compound is prepared by the procedure of Example 8, starting from tert.-butyloxycarbonyl proline polystyrene resin, and introducing the following amino acids stepwise: nitroarginine, proline, tryptophane and pyroglutamic acid. The nitro group is removed by hydrogenolysis at the end of the synthesis.

EXAMPLE 31 Pyr-Trp-Pro-His-Pro The title compound is prepared by the procedure described in Example 30 using N-b-utyloxycarbonyl-N dinitrophenyl histidine (4.6 g.) in dichloromethane (45 ml.) for the introduction of the histidyl residue.

EXAMPLE 3 2 N -Pyr-Lys-Trp-Ala-Pro 1. tert.-Butyloxycarbonyl Ala-Pro-benzyl ester.Proline benzyl ester hydrochloride (16.5 g.) is dissolved in DMF (342 ml.). The solution is cooled to 0 C. and TEA (9.8 ml.) and tert.-butyloxycarbonyl-alanine p-nitrophenyl ester (20.2 g.) are added. After 21 hours at room temperature, the solvent is removed in vacuo and the residue is dissolved in ethyl acetate, washed with 20% aqueous citric acid, water, saturated sodium bicarbonate and water. The organic phase is dried over magnesium sulfate and concentrated to dryness in vacuo. The residue is dissolved in ether and the product precipitated by addition of hexane.

2. tert.-Butyloxycarbonyl-Trp-Ala-Pro benzyl-ester.-- The protected dipeptide of paragraph 11 (25 g.) is dissolved in cold trifiuoroacetic acid (100 ml.). After minutes at room temperature most of the trifluoroacetic acid is removed in vacuo. The oily residue is solidified by trituration with ether. This dipeptide trifiuoroacetate is dissolved in a mixture of dimethylformamide (300 ml.), triethylamine (88 ml.) and tert.-butyloxycarbonyl-tryptophane 2,4,5-trichloropheny1 ester (26 g.). After 24 hours at room temperature, the reaction mixture is worked up as described in paragraph 1. r

3. N 'tert.-Butyloxycarbonyl-N benzyloxycarbonyk Lys-Trp-Ala-P'ro-benzyl ester. -The protected tripeptide of paragraph 2 is treated with trifluoroacetic acid and the resulting tripeptide benzyl ester trifiuoroacetate (6.7 g.) is dissolved in a mixture of dimethylformamide, (60 ml.), triethylamine (1.67 ml.) and N-tert.-butyloxycarbonyl-N- benzyloxycarbonyl lysine p-nitrophenyl ester (5.8 g.). After 18 hours at room temperature, the reaction mixture is worked up as described in paragraph 1.

- 4.- N"-tert.-Butyloxycarbonyl-Lys-Trp A1a-Pro.-The protected tetrapeptide of paragraph 3 (0.8 g.) is dissolved in a mixture of methanol (9 ml.), water (1 ml.) and glacial acetic acid (0.2 ml.). After addition of 10% palladium on charcoal (200 mg.), the mixture is hydrogenated at normal pressure for 5 hours. The catalyst is filtered off and the filtrate concentrated to dryness in vacuo to yield the title compound.

"5. N-PyrLys-Trp-Ala-Pro.The partially protected tetrapeptide of paragraph 4 is dissolved in a mixture of DMF (40 ml.), TEA (1 ml.) and pyroglutamic acid 2,4}5-trichlorophenyl ester (2.1 g.). After 17 hours at room temperature, the reaction mixture is worked up as described in paragraph 1 The partially protected pentapeptide thus obtained is treated with trifluoroacetic acid to remove the tert.-butyloxycarbonyl group.

EXAMPLE 33 Pyr-His-Trp-tAla-Pro l-tert. ButyloxycarbonyI His-Trp-AIa-Pro-benzy1 ester.-Trp-Ala-Pro-benzyl ester trifluoroacetate (see paragraph 3 of Example 32) is allowed to react with tert.- butyloxycarbonyl-histidine azide ['see I. A. C. S., 4711 (1968)] and the protected tetrapeptide is isolated as described in paragraph 1 of Example 32, but eliminating the citric acid washing.

2. Pyr-His-Trp-Ala-Pro.-The protected tetrapeptide of paragraph 1 is treated with trifiuoroacetic acid as in paragraph 2 of Example 32. The resulting trifluoroacetate is dissolved in a mixture of DMF (40 ml.), TEA (1 ml.) and pyroglutamic acid 2,4,S-trichlorophenyl ester- (2.1 g.). After 17 hours at room temperature, the reaction mixture is worked up as described in paragraph 1 of Example 32. The protected pentapeptide ester is deprotected by catalytic hydrogenolysis.

EXAMPLE 34 Pyr-Isys-Phe-Ala-Pro Starting with 8 g. of tert.-butyloxycarbonyl-proline polystyrene resin (containing 0.187 mmoles of proline per gram of resin) and following the procedure of Example 7, the following amino acids are introduced sequentially: Boc-Ala; Boc-Phe; ot-Bos-e-Z-Lys; and Pyr. In the latter case the solvent is a mixture of dichloromethane and dimethylformamide (2.5:1). The pentapeptide is re-' moyed from the resin with hydrobromic acid in trifiuoroacetic acid. After concentration in vacuo, the free pentapeptide is isolated by precipitation with ether.

EXAMPLE 35 "Pyr-Lys-Trp-Ile-Pro fromrthqresin.iscarried;outas-in Example 10.

1 Pyt-Lys-Trp-Thr-Pro I Thetitle-coinpound prepared as described for the compound;. of Example, 3 5 but substitutingthreonine for issal ue ne; a

19 EXAMPLE 37 Pyr-Lys-TrpqAla-Gly EXAMPLE 38 Pyr-Lys-Trp-Ala-Sar The title compound is prepared as described for the compound of Example 37 starting from butyloxycarbonylsarcosine polystyrene resin.

EXAMPLE 39 Pyr-Nle-Trp-Ala-Pro The title compound is prepared according to the procedure described in Example 8, except using tert.-butyloxycarbonyl norleucine for the introduction of the norleucyl residue prior to introduction of the pyroglutamic acid.

EXAMPLE 40 Pyr-His-Trp-Ala-Pro The title compound is prepared according to the procedure described in Example 8, except using N"-butyloxycarbon-N -dinitrophenyl histidine for the introduction of the histidyl residue prior to introduction of the pyroglutarrn'c acid.

EXAMPLE 41 Pyr-Orn-Trp-Ala-Pro Pyr-Trp-Pro-Arg-Pro-Thr-Pro-Gln-Ile-Pro-Pro 1. Gln-Ile-Pro-Pro.-The title compound is prepared starting with tert.-butyloxycarbonyl-proline polystyrene resin (8 g.) containing ca. 0.5 meq. of proline per gram and is allowed to stir overnight with dichloromethane. The dichloromethane is removed by filtration and the resin is submitted to the procedure set forth in-Example 8 introducing stepwise the following amino acid residue: proline, isoleucine and glutamine, employing tertl-butyloxycarbonyl groups for amino protection in each case.

The tetrapeptide resin is then suspended in trifluoroacetic acid (100 ml.). Hydrogen bromide is bubbled through while cooling the flask in an ice-water mixture. After 35 minutes, the resin is filtered olf and washed twice with trifluoroacetic acid and four times with a mixture of trifluoroacetic acid and dichloromethane (1:1). The combined filtrates are evaporated to dryness and the residue triturated with ether. The solid is filtered and dried to yield the free tetrapeptide. t

' 2. Pyr-Trp-Pro-Arg-Pro-ihr-Prm-Staitingfrom tert.- butyloxycarbonyl-proline resin, six cycles of deprotection and coupling are carried out as described in Example 34. The amino acid derivatives used are: tert.-butyloxycarbonylproline; tert. butyloxycarbonyl-O-benzyl-threonine; tert.-butyloxycarbonyl-proline; tert.-butyloxycarbonyl-nitroarginine; tert.-butyloxycarbonyl-proline, terL-butyloxycarbonyl tryptophan and pyroglutamic acid. In the case of the nitroarginine, tryptophan and pyroglutamic acid residues, the solvent is a mixture of dichloromethane and dimethylformamide (2.5 1). The partially deprotected Bzl peptide (Pyr-Trp-Pro-NO -Arg-Pro-ii"hr-Pro) is removed from the resin with hydrobromic acid in trifluoroacetic acid (containing anisol and mercaptoethanol).

3. Pyr-Trp-Pro-Arg-Pro-Thr-Pro-Gln-Ile-Pro-Pro.The heptapeptide acid of paragraph 2 1 .1 (Pyr-Trp-Pro-NO -Ar g-Pro-Thr-Pro) is coupled with Gln-Ile-Pro-Pro using the mixed carboxylic carbonic anhydride procedure. The protecting groups are removed by hydrogenolysis at the end of the synthesis.

EXAMPLE 43 Pyr-Gly-Gly-Trp-Pro-Arg-Pro-Gly-Pro-Gln-Ile-Pro-Pro Starting from 10 g. of butyloxycarbonyl-proline resin (0.2 mmole proline per gram of resin) the following amino acids are attached: proline, isoleucine, glutamine, proline, glycine, proline, nitro-arginine, tryptophane, glycine, glycine and pyroglutamic, following the technique described for Example 34. In the case of the nitroarginine, tryptophane and pyroglutamic acid residues, the solvent is a mixture of dichloromethane and dimethylformamide (2.521). Tert.-butyloxycarbonyl protection for the amino group is used throughout the synthesis except for Pyr. Dicyclohexylcarbodiimide is used for all the coupling steps except for glutamine where the nitrophenyl ester is used. Removal of the compound from the resin is carried out as in Example 8. The protecting groups are then removed by hydrogenolysis.

EXAMPLE 44 Pyr-Gly-Gly-Trp-Pro-Arg-Pro-Gly-Pro-Glu-Ile-Pro-Pro The title compound is prepared by the procedure of Example 43 using -benzyl tert.-butyloxycarbonyl-glutamic acid instead of butyloxycarbonyl glutamine.

EXAMPLE 45 Pyr-Trp-Pro-Ang-Pro-Thr-Pro-Glu-Ile-Pro-Pro- EXAMPLE 46 Pyr-Trp-Pro-Ang-Pro-Gly-Pro-Gln-Ile-Pro-Pro The title compound is prepared as described for Example 43 except that pyroglutamic acid is introduced following tryptophane.

EXAMPLE 47 I Pyr-Trp-Pro-Arg-Pro-Gly Pro-Glu-Ile-Pro-Pro The title compound is prepared as described for Example 46 using 'y-benzyl-butyloxycarbonyl-glutamic acid and dicyclohexylcarbodiimide instead of glutamine.

EXAMPLE 48 Pyr-Lys-His-Ala-Pro The title compound is prepared as described for Example 34 using N-butyloxycarbonyl-N -dinitrophenyL 21 histidine for the introduction of the histidine residue in place of phenylalanine.

EXAMPLE 49 Pyr-Arg-Trp-Ala-Pro The title compound is prepared as described for Example 8 using t-butyloxycarbonyl arginine for the introduction of the arginine residue prior to introduction of the pyro glutamic acid. After removal of the peptide from the resin, deprotection is achieved by hydrogenolysis.

EXAMPLE 50 Pyr-Trp-Pro-Arg-Pro-Gly-Pro-Glu-Ile-Pro-Pro 1. Glu-Ile-Pro-Pro.The title compound is prepared following the procedure of part 1 of Example 42 except substituting t-butyloxy-carbonyl glutamic acid-'y-benzyl ester and dicyclohexyl-carbodiimide for t-butyloxycarbonyl-glutamine p-nitrophenyl ester.

2. Pyr-Trp-Pro-Arg-Pro-Gly-Pro.The title compound is prepared according to the procedure of part 2 of Example 42 except substituting t-butyloxycarbonyl glycine in place of t-butyloxycarbonyl-O-benzyl threonine.

3. Pyr-Trp-Pro-Arg-Pro-Gly-Pro-Glu Ile Pro Pro.- The heptapeptide of paragraph 2 is coupled with the tetrapeptide of paragraph 1 according to the procedure of part 3 of Example 42.

EXAMPLE 51 Pyr-Trp-Pro-Arg-Pro-Thr-Pro-Gln-Ile-Pro-Pro 2. Pyr-Trp-Pro-Arg-Pro.4tarting from tert.-butyloxycarbonyl proline resin polystyrene resin containing about 0.5 mmole of proline per gram of resin, the series of reactions described in Example 7 are repeated introducing sequentially tert.-butyloxycarbonyl nitroanginine, Boc-Pro, Boc-Trp, and Pyr. The pentapeptide resin is suspended in trifluoroacetic acid (100 ml.) containing mercaptoethanol (1 ml.) and anisole (2 ml.). Hydrogen bromide is bubbled through while cooling the flask in an icewater mixture. After 35 minutes, the resin is filtered on and washed twice with trifluoroacetic acid and four times with a mixture of trifluoroacetic acid and dichloromethane (1:1), containing mercaptoethanol and anisole. The combined filtrates are evaporated to dryness and the residue triturated with ether. The solid is filtered and dried.

3. Pyr-Trp-Pro-Arg-Pro-Thr-Pro-Gln-Ile-Pro-Pro.-The hexapeptide of paragraph 1 is coupled with the pentapeptide of paragraph 2 using the mixed carboxylic carbonic anhydride procedure. The protecting groups are removed by hydrogenolysis at the end of the synthesis.

EXAMPLE 52 Pyr-Ile-Pro-Pro-Lys-Phe-Ala-Pro 22 vacuo, the free octapeptide is isolated by precipitation with ether.

EXAMPLE s3 1. 3 L- tert. Butyloxycarbonylamino-4-phenylbutyric acid (Boc-,3Hphe).--To a solution of tert.-butyloxycarbonyl-L-phenylalanine (13.2 g.) in a mixture of ether (100 ml.) and TEA (7 ml.), chilled to 5 C., ethyl chloroformate (4.8 ml.) is added. After stirring for 10 minutes at -5, the precipitate is filtered off and the filtrate added to a solution of diazomethane (prepared from 20 g. of N-methyl-N'-nitro-N-nitrosoguanidine) The solution is stored at 5 C. overnight. The solvent is removed in vacuo and the residue crystallized from ethyl acetatehexane.

This crystalline material (9.1 g.) is dissolved in methanol (62 ml.) and stirred at room temperature after addition of a few drops of a solution of silver benzoate (1 g.) in triethylamine (9.1 g.). When the evolution of nitrogen stops, the precipitate formed is filtered oil", and the filtrate is concentrated to dryness. The residue is crystallized from hexane.

This crystalline material (5 g.) is dissolved in a mixture of methanol (50 ml.) and sodium hydroxide (34 ml.). After storing the solution for 2 hours at room temperature, N hydrochloric acid is added to neutralize the excess base, the methanol is removed in vacuo, and the desired product extracted with ethyl acetate after acidification.

2. Pyr-Lys-pHphe-Ala-Pro.-The title compound is prepared following the procedure described in Example 7 utilizing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids.

EXAMPLE 5 4 cpc-Trp-Pro Gly-Pro-Lys-BHphe-Ala-Pro The title compound is prepared as described in Example 10, utilizing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids and Cpc. The preparation of Boc-pHphe is described in Example 53.

EXAMPLE Pyr-Lys-Phe-Ala-Pro-Pro The title compound is prepared as described in Example 34 but introducing Boo-Pro before Boc-Ala.

EXAMPLE 56 Pyr-Lys-Phe-Ala-Pro-Gln-Ile-Pro-Pro The title compound is prepared according to the procedure described in Example 10, utilizing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids except for Pyr. In the case of glutamine the p-nitrophenyl ester is used instead of the dicyclohexylcarbodiimide procedure for the coupling step.

EXAMPLE 57 Pyr-Lys-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared according to the procedure described in Example 10, utilizing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids except for Pyr. In the case of glutamine the p-nitrophenyl ester is used instead of the dicyclohexylcarbodiimide procedure for the coupling step.

EXAMPLE 58 Pyr-Glu-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared according to the procedue described in Example 57 except introducing the glutamyl residue as the B-benzyl ester in place of a-BOC-e-Z- Lys. In the case of glutamine, the p-nitrophenyl ester is used instead of dicyclohexylcarbodiimide in the coupling step.

residue.

EXAMPLE 9 Pyr-Phe-Pro-Arg-PrmGln-Ile-Pro-Pro The title compound is prepared by the procedure described in Example 10, utilizing the tert.-butyloxycarbonyl derivatives of the corresponding amino acids except for Pyr. In the case of glutamine the p-nitrophenyl ester is used instead of dicyclohexylcarbodiirnide for the coupling step.

EXAMPLE 6O Pyr-Trp-Pro-Arg Pro-Nle-Ile-Pro-Pro The title compound is prepared by the procedure described in Example 59, but utilizing tert.-butyloxycarbonyl norleucine in place of tert.-butyloxycarbonyl isoleucine.

EXAMPLE 61 Pyr-Trp-Pro-Arg-Pro-Gln-Phe-Pro-Pro The title compound is prepared by the procedure described in Example 59, but utilizing tert.-butyloxycarbonyl phenylalanine in place of tert.-butyloxycarbonyl isoleucine.

EXAMPLE 62 Pyr-Trp-Pro-Orn-Pro-Gln-Ile-Pro-Pro The title compound is prepared by the procedure described in Example utilizing the tert.-butyl0xycarbonyl derivatives of the corresponding amino acids except for Pyr. The fi-amino group of Orn is temporarily protected with a benzyloxycarbonyl residue. In the case of the glutamine residue, the nitrophenyl ester is used in the coupling step.

EXAMPLE 63 Pyr-Lys-Phe-Ala-Ala The title compound is prepared starting from tert.- butyloxycarbonyl-alanine polystyrene resin containing about 0.5 mmole alanine per gram and following the procedure of Example 34.

carbonyl proline.

EXAMPLE 66 Pyr-Trp-Pro-Arg-Pro-Nle-Phe-Ala-Pro The title compound is prepared following the procedure of Example 65 but utilizing tert.-butyloxycarbonylphenylalanine in lieu of tert.-butyloxycarbonyl-isoleucine.

EXAMPLE 67 Pyr-Trp-Pro-'Orn-Pro-Nle-lle-Pro-Pro The title compound is prepared following the procedure of Example 60 but utilizing ter-t. butyloxycarbonyl ornithine in lieu of u-Boc-w-nitro-Arg. The fi-amino group of Orn is temporarily protected with a benzyloxycarbonyl EXAMPLE 68 Pyr-Trp-Pro-orn-Pro-Nle-Phe Pro-Pro The title compound is prepared following the procedure of Example 67 but utilizing tert.-butyloxycarbonyl phenylalanine in lieu of tert.-butyloxycarbonyl isoleucine.

EXAMPLE 69 Pyr-Trp-Pro-Orn-Pro-Nle-lle-Ala-Pro The title compound is prepared following the procedure of Example 65, but utilizing -tert.-butyloxycarbonyl-6 benzyloxycarbonyl ornithinein lieu of a -BOC-q-nitlO AIg.

EXAMPLE 70 I lPyr-Trp-Pro-Orn-Pro-Nle-Phe-Ala-Pro The title compound is prepared following the procedure of Example 69, but utilizing tert.-butyloxycarbonyl phen ylalanine in lieu of tert.-butyloxycarbonyl isoleucine.

EXAMPLE 71 Pyr-Trp-Pro-Arg-Pro-Gln-Phe-Ala-Pro The title compound is prepared following the procedure of Example 60, but utilizing tert.-'butyloxycarbonyl glutamine in lieu of tert.-butyloxycarbonyl norleucine. 'In the case of glutamine, the p-nitrophenyl ester is used for the coupling step.

EXAMPLE 72 Pyr-TrpaPro-Orn-Pro-Gln Phe-Pro-Pro The title compound is prepared following the procedure of Example 68, but utilizing tert.-butyloxycarbonyl glutamine in lieu of tert.-butyloxycarbonyl norleucine.

EXAMPLE 73 Pyr-Trp-Pro-Orn-Pro-Gln-Ile-Ala-Pro The title compound is prepared following the procedure of Example 72, but utilizing tert.-butyloxycarbonyl isoleucine in lieu of tert.-butyloxycarbonyl phenylalanine.

EXAMPLE 74 Pyr-Trp-Pro-Orn-Pro-Gln-Phe-Ala-Pro The title compound is prepared following the procedure of Example 73, but utilizing te-rt.-butyloxycarbonyl phenylalanine in lieu of tert.-butyloxycarbonyl isoleucine.

EXAMPLE 75 Pyr-Gly-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 59, but utilizing tert.-butyloxyca rbonyl glycine in lieu of tert.-butyloxycarbonyl phenylalanine.

EXAMPLE 76 Cpc-Gly-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 2, but utilizing tert.-butyloxycar-bonyl glycine in lieu of tert.-butyloxycarbonyl phenylalanine.

EXAMPLE 77 Pyr-Leu-Pro-Arg-Pro-Gln-lle-Pro-Pro The title compound is prepared following the procedure of Example 75, but utilizing tert.-'butyloxycarbonyl leucine in lieu of tert.-butyloxycarbonyl glycine.

EXAMPLE 78 Cpc-Leu-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 76, but utilizing tert.-butyloxycarbonyl leucine in lieu of tert.-butyloxycarbonyl glycine.

EXAMPLE 79 Pyr-D-Trp-Pro-Arg-Pro=Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 75, but utilizing tert.-butyloxycarbonyl D- tryptophane in lieu of tert.-butyloxycarbonyl glycine.

up to the step of removing the tetrapeptide from the resin. The N-terminal prolyl residue is then introduced by shaking the tetrapeptide resin with a solution of tert.-butyloxycarbonyl proline (2.57 g.) in dichloromethane (56 ml.) for 20 minutes. A solution of dicyclohexylcarbodiimide (2.5 g.) in dichloromethane is added and the shaking continued for 3 hours. The resulting peptide is removed from the resin and obtained as the free pentapeptide as described in paragraph 2 of part 1 of Example 42.

2. Arg-Pro-Gln-Ile-Pro-Pro. The pentapeptide of paragraph 1 is coupled with benzyloxycarbonyl nitroarginine 2,4-dinitrophenyl ester using the procedure of paragraph 7 of Example 1 but eliminating the washing with ammonia. The protected hexapeptide is subjected to hydrogenolysis to yield the title hexapeptide.

3. -Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro. The hexapeptide of paragraph -2 is' coupled to the tripeptide Pyr- Trp-Pro following the procedureof paragraph 9 of Example 1 to yield the title compound.

EXAMPLE 82 Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Pro Pro EXAMPLE 83 Pyr-Trp-Pro-Arg-Pro-Thr-Pro-Gln-Ile-Pro-P1 o 1. Pro-Thr-Pro-Gln-Ile-Pro-Pro.The title compound is prepared following the procedure of paragraph 1 of Example 51 up to the stage of removing the hexapeptide from the resin. The N-terminal prolyl residue is then introduced following theprocedure of paragraph 1 of Example 81. The resulting peptide is removed from the resin and obtained as the free heptapeptide following the procedure of paragraph 2 of part- 1 of Example 42.

2. Arg-Pro-Thr-Pro-Gln-l]e-Pro-Pro.--The title compound is prepared by coupling benzoyloxycarbonyl nitroarginine 2,4-dinitrophenyl ester .to the heptapeptide of paragraph 1 by the procedure of paragraph 2 of Example 81. a I

i 3. Pyr-Trp-Pro-Arg-Pro Thr Pro-Gln-Ile-Pro-Pro.- The title compound is prepared by coupling the octapeptide of paragraph 2to the tripeptide Pyr-Trp-Pro following the procedure of paragraph 9 of Example 1.

p EXAMPLE s4 Pyr-Trp-Pro-Arg-Pro-Thr-Pro-Gln-Ile-Pro-Pro 1. Pro-ArgrPro-Thr-Pro-Gln Ile Pro-Pro.The title compound is prepared following. the procedure of Example 10 introducing the following protected amino acids sequentially: BocPro, Boo-Ile, Boc-Gln, Boc-Pre, Boc-O- Bzl-Thr, BocPro, a-Boc-w-nitro-Arg and Boc-Pro. The peptide is removed from the resin as described in paragraph 9 of Example ,7- to yield the free nonapeptide. The remaining protecting groups are then removed by hydrogenolysis. l

2. Trp-Pro-Arg-Pro-Thr Pro Gln-Ile-Pro-Pro.-'Ihe title compound is prepared by couplingtert.-butyloxycar- 26 bonyl tryptophan 2,4,5 trichlorophenyl ester to the nonapeptide of paragraph 1 according to the procedure of paragraph 2 of Example 1.

3. Pyr-Trp-Pro-Arg-Pro Thr Pro-Gln-Ile-Pro-Pro.- The title compound is prepared by coupling pyroglutamic acid 2,4,5 trichlorophenyl ester to the decapeptide of paragraph 2 following the procedure of paragraph 2 of Example 1.

EXAMPLE Pyr-Trp-Pro-Arg-Pro-Thr-Pro-Glu-Ile-Pro-Pro 1. GluIle-Pro-Pro.-The title compound is prepared following the procedure of paragraph 1 of Example 42 except substituting tert.-butyloxycarbonyl glutamic acid- 'y-benzyl ester and dicyclohexylcarbodiimide for Boo-Gln.

2. Pyr-Trp-Pro Arg-Pro Thr Pro-Glu-Ile-Pro-Pro.- The title compound is prepared by coupling the tetrapeptide of paragraph 1 to the heptapeptide acid prepared as described in paragraph 2 of Example 42 following the procedure of paragraph 3 of Example 42.

EXAMPLE 86 Pyr-Trp-Pro-Arg-Pro-Gly-Pro-Glu-Ile-Pro-Pro 1. Pyr-Trp-Pro-NO -Arg-Pro-Gly-Pro.'Ihe title compound is prepared following the procedure of part 2 of Example 42, but substituting Boc-Gly for tert.-butyloxycarbonyl-O-benzyl-threonine.

2. Pyr-Trp-Pro-Arg Pro Gly-Pro-Glu-Ile-Pro-Pro. The title compound is prepared by coupling the tetrapeptide of paragraph 1 of Example 85 to the heptapeptide acid of paragraph 1 following the procedure of part 3 of' Example 42.

EXAMPLE 87 Pyr-Trp-Pro-Gly-Pro-Glu-Ile-Pro-Pro 1. Gly-Pro-Glu-Ile-Pro-Pro.--The title compound is prepared following the procedure of paragraph 1 of Example 51, but substituting tert.-butyloxycarbonyl glycine in lieu of tert.-butyloxycarbonyl-O-benzyl threonine and Boc-Glu in lieu of Boo-Gln.

2. Pyr-Trp-Pro-Gly-Pro Glu Ile-Pro-Pro.The title compound is prepared by coupling the tripeptide Pyr-Trp- Pro to the hexapeptide of paragraph 1 following the procedure of paragraph 9 of Example 1.

EXAMPLE 88 Pyr-Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro 1. Pro-Gly-Pro-Gln-Ile-Pro-Pro.The title compound is prepared following the procedure of paragraph 1 of Example 83, but substituting tert.-butyloxycarbonyl glycine for tert.-butyloxycarbonyl-O-benzyl threonine.

2. Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro.-The title compound is prepared by coupling tert.-butyloxycarbonyl tryptophan 2,4,5-trichlorophenyl ester to the heptapeptide of paragraph 1 according to the procedure of paragraph 2' of Example 1.

3. Pyr-Trp-Pro-Gly-Pro Gln Ile-Pro-Pro.The title compound is prepared by coupling pyroglutamic acid 2,4,5-trichlorophenyl ester to the octapeptide of paragraph 2 following the procedure of paragraph 2 of Example 1.

EXAMPLE 89 Pyr-Trp-Pro-Arg-Pro-Gly-Pro-Gln-Ile-Pro-Pro 1. Arg-Pro-Gly-Pro-Gln-Ile-Pro-Pro.-The title compound is prepared following the procedure of paragraph 2 of Example 83, but substituting tert.-butyloxycarbonyl glycine in lieu of tert. butyloxycarbonyl O benzyl threonine.

2. Pyr-Trp-Pro-Arg Pro Gly-Pro-Gln-Ile-Pro-Pro.- The title compound is prepared by coupling the octapeptide of paragraph 1 to the tripeptide Pyr-Trp-Pro following the procedure of paragraph 9 of Example 1.

EXAMPLE 90 Pyr-Trp-Pro-Arg-Pro-Gly-Pro-Gln-Ile-Pro-Pro of paragraph 2 following the procedure of paragraph 2 of Example 1.

EXAMPLE 91 Pyr-Asu-Trp-Pro-His-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 57, but utilizing N-tert.-butyloxycarbonyl- N dinitrophenyl histidine (4.6 g.) in DCM (45 ml.) in lieu of tert.-butyloxycarbonyl w nitroarginine, and utilizing tert.-butyloxycarbonyl asparagine p-nitrophenyl ester (1.42 g.) in a mixture of DMF (7 ml.) and DCM (21 ml.) in lieu of N -tert.-butyloxycarbonyl-N-benzyloxycarbonyl lysine. The N -dinitrophenyl protecting gitlmsp is removed by treatment with mercaptoethanol at p EXAMPLE 92 Pyr-Ser-TrpPro-Gly-Pro-Asn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 91 but (1) introducing tert.-butyloxycarbonylasparagine p-nitrophenyl ester (3.54 g.) in a mixture of DMF (15 ml.) and DCM (41 ml.) in lieu of glutamine, (2) introducing tert.-butyloxycarbonyl glycine in lieu of N-tert.-buty1oxycarb0nyl N dinitrophenyl histidine, and (3) using tert.-butyloxycarbonyl-O-benzyl-serine and dicyclohexylcarbodiimide to introduce serine in lieu of tert.-butyloxycarbonyl-asparagine p-nitrophenyl ester.

EXAMPLE 93 Pry-Ser-Trp-Pro-His-Pro-Gln-lle-Pro-Pro The title compound is prepared as described for the compound of Example 91, except using tert.-butyloxycarbonyl-O-benzyl-serine and dicyclohexylcarbodiimide to introduce the seryl residue in lieu of tert.-butyloxycarbonyl-asparagine p-nitrophenyl ester.

EXAMPLE 9'4 Pyr-Nle-Trp-Pro-I-Iis-Pro-Gln-Ile-Pro-[Pro The title compound is prepared as described for the compound of Example 91, except using t-butyloxycarbonyl-norleucine and dicyclohexylcarbodiimide to introduce the norleucyl residue in lieu of tert.-butyloxycarbonyl-asparagine p-nitropheny1 ester.

EXAMPLE 95 Pyr-Asn-TrpeTPro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared as described for the compound of Example 91, except using t-butyloxycarbonyl-nitroarginine for the introduction of the arginyl residue in place of N"-t-butyloxycarbonyl-N -dinitrophenyl histidine. The nitro protecting group of the nitroarginine residue is removed by hydrogenolysis at the end of the synthesis.

EXAMPLE 9 6i Pyr-Ser-Trp-Pro-Lys-Pro-Gln-Ile-Pro-Pro The title compound is prepared as described for the compound of Example 93, except using N-t-butyloxy- 28 carbonyl-N-trifluoroacetyl lysine for the introduction of the lysyl residue in place of N-t-b utyloxycarbony1-N dinitrophenyl histidine. The trifluoroacetyl protecting group is removed by treatment with piperidine at the end of the synthesis. 1

EXAMPLE 97 Pyr-Asn-Trp-ZPro-Hlis-Pro-Gln-Ile-Pro-Pro l. Pyr-Asn-Trp-Pro-His-Pro.Starting from t-butyloxycarbonyl prolyl resin, the title compound is prepared by following the procedure of Example 91 but omitting those operations required to introduce the sequence Gln- Ile-Pro-Pro.

2. Pyr-Asn-Trp-Pro-His-Pro-Gln-Ile Pro Pro.The title compound is prepared by coupling the tetrapeptide Gln-Ile-Pro-Pro prepared as described in part 1 of Example 42 to the hexapeptide of paragraph 1 according to the procedure of part 3 of Example 42.

EXAMPLE 98 Pyr-Ser-Trp-Pro-His-Pro-G'ln-flle-Pro-Pro 1. Pyr-Ser-Trp-Pro-His-Pro.--The title compound is prepared as described for the compound of paragraph 1 of Example 97 except using t-butyloxycarbonyl-O-benzyl serine and dicyclohexylcarbodiimide to introduce the seryl residue in lieu of tert.-butyloxycarbonyl-asparagine p-nitrophenyl ester.

2. Pyr-Ser-Trp-Pro-His-Pro-Gln Ile Pro Pro.'Ihe title compound is prepared by coupling the tetrapeptide Gln-Ile-Pro-Pro to the hexapeptide of paragraph 1 according to the procedure of part 3 of Example 42.

EXAMPLE 99 Pyr-Ser-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro Pyr-Nle-Trp-Pro-Lys-Pro-Gln-Ile-Pro-Pro Tfa 1. Pyr-Nle-Trp-Pro-l.ys-Pro.--The title compound is prepared as described for the compound of paragraph 1 of Example 97, except using N -t-butyloxycarbonyl-N -trifluoroacetyl lysine to introduce the lysyl residue in place of N-t-butyloxycarbony1-N -dinitrophenyl histidine, and using t-butyloxycarbonyl-norleucine to introduce the norleucyl residue in lieu of tert.-butyloxycarbonyl asparagine p-nitrophenyl ester. l

2. Pyr-Nle-Trp-Pro-Lys-Pro-Gln Ile Pro Pro.The title compound is prepared by coupling the tetrapeptide Gln-Ile-Pro-Pro to the hexapeptide of paragraph 1 according to the procedure of part 3 of Example 42. The trifluoroacetyl group is removed by treatment with piperidine at the end of the synthesis. i

EXAMPLE 1 0 1 Pyr-Ser-Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro introduce the glycine residue in lieu of N-t-butyloxycarbonyl-N' -dinitrophenyl histidine.

29 2. Pyr-Ser-Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro.The title compound is prepared by coupling the hexapeptide acid of paragraph. 1, Pyr-Ser-Trp-Pro-Gly-Pro, to the tetrapeptide, Gln-Ile-Pro-Pro, prepared according to the procedure s'etforth in part 1 of Example 42, using the mixed carboxylic carbonic anhydride procedure to effect the coupling.

. i 7 EXAMPLE 102 Pyr-Trp- Pro-Ar'g-Pro-Gln-Ile-Pro-Pro The title compound is prepared as described for the compound of Example 91, except using t-butyloxycarbonyl-nitroarginine in place of N"-t-butyloxycarbonyl- N -dinitrophenyl histidine, and omitting those steps required for incorporation of the asparaginyl residue. The removal of the nitro group from the nitro nonapeptide is achieved by hydrogenolysis at the end of the synthesis.

EXAMPLE 103 Pyr-Asn-Trp-Pro-Arg-Pro-Asn-Ile-Pro-Pro The title compound is prepared as described for the compound of Example 95 except substituting tert.-butyloxycarbonyl asparagine p-nitrophenyl ester for tert.-butyloxycarbonyl glutamine p-nitrophenyl ester to introduce the asparaginyl residue in lieu of the glutaminyl residue.

EXAMPLE 104 Pyr-Ser-Trp-Pro-Arg-Pro-Asn-Ile-Pro-Pro The title compound is prepared as described for the compound of Example 92 except using tert.-butyloxycarbonylnitroarginine to introduce the arginyl residue in lieu of tert.-butyloxycarbonyl glycine. The nitro protecting group of the nitroarginine residue is removed by hydrogenolysisat the end of the synthesis.

I EXAMPLE 105 Pyr-Nle-Trp-Pro-Arg-Pro-Asn-Ile-Pro-Pro The title compound is prepared as described for the compound of Example 104, except using t-butyloxycarbonylnorleucine and dicyclohexylcarbodiimide to introduce the norleucyl residue in lieu of the serine residue.

EXAMPLE 106 Pyr-Trp-Pro-Arg-Pro-Asn-Ile-Pro-Pro The title compound is prepared as described for the compound of Example 104, except eliminating the procedures required to introduce the seryl residue.

EXAMPLE 107 Pyr-Asn-Trp-Pro-His-Pro-Asn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 91 except introducing asparagine in place of glutamine according to the procedure of Example 92.

EXAMPLE 110 Pyr-Trp-Pro-His-ProAsn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 107, except eliminating the steps required to 30 insert the asparaginyl moiety after introduction of the tryptophyl moiety.

EXAMPLE 111 Pyr-Asn-Trp-Pro-Lys-Pro-Asn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 107, except using N- -butyloxycarbonyl-N- trifluoroacetyl lysine for the introduction of lysine in place of N-t-butyloxycarbonyl-N -dinitrophenyl histidine. The trifiuoroacetyl group is removed by treatment with piperidine at the end of the synthesis.

EXAMPLE 112 Pyr-Ser-Trp-Pro-Lys-Pro-Asn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 96, except introducing asparagine in place of glutamine as described in Example 103.

EXAMPLE 1 13 Pyr-Nle-Trp-Pro-Lys-Pro-Asn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 111, except using tert.-butyloxycarbonylnorleucine and dicyclohexylcarbodiimide to introduce the norleucyl residue after the tryptophyl residue in lieu of the asparaginyl residue.

EXAMPLE 114 I Pyr-Trp-Pro-Lys-Pro-Asn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 113, except eliminating those steps required to introduce the norleucyl residue after introduction of the tryptophyl residue.

EXAMPLE 11S Pyr-Asn-Trp-Pro-Gly-Pro-Asn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 92, except using tert.-butyloxycarbonylasparagine p-nitrophenyl ester to introduce the asparaginyl residue in lieu of the seryl residue.

EXAMPLE 1 16 Pyr-Nle-Trp-Pro-Gly-Pro-Asn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 92, except using t-butyloxycarbonylnorleucine and dicyclohexylcarbodiimide to introduce the norleucyl residue in lieu of t-butyloxycarbonyl-O-benzyl serine and dicyclohexylcarbodiimide.

EXAMPLE 117 Pyr-TrpPro-Gly-Pro-Asn-Ile-Pro-Pro The title compound is prepared following the procedure of Example 114 except using t-butyloxycarbonyl glycine in place of N t butyloxycarbonyl N-trifluoroacety1 lysine.

EXAMPLE 118 Pyr-Ser-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 93, except using t-butyloxycarbonyl nitroarginine for the introduction of the arginyl residue in lieu of N -t butyloxycarbonyl-N dinitrophenyl histidine. The nitro protecting group of the nitroarginine residue is removed by hydrogenolysis at the end of the synthesis.

EXAMPLE 119 Pyr-Nle-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 94, except using t-butyloxycarbonyl nitroarginine for the introduction of the arginyl residue in lieu of N-t-butyloxycarbonyl-N dinitrophenyl histidine.

The nitro protecting group of the nitroarginine residue is removed by hydrogenolysis at the end of the synthesis.

31 I EXAMPLE 120 Pyr-Trp-Pro-His-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 102, except using N-t-butyloxycarbonyl- N -dinitropheny1 histidine in lieu of t-butyloxycarbonyl nitroarginine.

EXAMPLE 121 Pyr-Asn-Trp-Pro-Lys-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 91, except using N-t-butyloxycarbonyl-N trifluoroacetyl lysine for the introduction of the lysyl residue in place of N -t-butyloxycarbonyl-N -dinitrophenyl histidine. The trifiuoroacetyl group is removed by treatment with piperidine at the end of the synthesis.

EXAMPLE 122 Pyr-Nle-Trp-Pro-Lys-Pro-Gln-I1e-Pro-Pro- The title compound is prepared following the procedure of Example 94, except using N -t-butyloxycarbonyl- -trifluoroacetyl lysine for the introduction of the lysyl residue in place of N-t-butyloxycarbonyl-N -dinitrophenyl histidine. The trifiuoroacetyl group is removed by treatment with piperidine at the end of the synthesis.

EXAMPLE 123 Pyr-Trp-Pro-Lys-Pro-Gln-Ile-PrmPro The title compound is prepared following the procedure of Example 102 except using N-t-butyloxycarbonyl-N- trifluoroacetyl lysine for the introduction of the lysyl residue in place of t-butyloxycarbonyl nitroarginine. The trifluoroacetyl group is removed by treatment with piperidine at the end of the synthesis.

EXAMPLE 124 Pyr-Asn-Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 95, except using t-butyloxycarbonyl glycine in place of t-butyloxycarbonyl nitroarginine.

EXAMPLE 125 Pyr-Ser-Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 93, except using t-butyloxycarbonyl glycine in lieu of N -t-butyloxycarbonyl-N -dinitropheny1 histidine.

EXAMPLE 126 Pyr-Nle-Trp-Gly-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 94, except using t-butyloxycarbonyl glycine in lieu of N-t-butyloxycarbonyl-N -dinitrophenyl histidine.

EXAMPLE 127 Pyr-Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 102, except using t-butyloxycarbonyl glycine in place of t-butyloxycarbonyl nitroarginine.

EXAMPLE 128 Pyr-Asn-Trp-Pro-Arg-Pro The title compound is prepared following the procedure of Example 91, except using t-butyloxycarbonyl nitroarginine for the introduction of the arginyl residue in place of N-t-butyloxycarbonyl-N -dinitrophenyl histidine, and eliminating those steps required for introduction of the Gln-Ile-Pro-Pro moiety. The nitro protecting group of the nitroarginine residue is removed by hydrogenolysis at the end of the synthesis.

32 EXAMPLE 129 Pyr-Nle-Trp-Pro-Arg-Pro The titlecompound is prepared following the procedure of paragraph 1 of Example except using t-butyloxycarbonyl nitroarginine for the introduction of the arginyl residue in place of N -t-butyloxycarbonyl-N -trifluoroacetyl lysine. The nitro protecting group of the nitroarginine residue is-removed by hydrogenolysis' at the end of the synthesis.

EXAMPLE 130 Pyr-Nle-Trp-Pro-His-Pro I The title compound is prepared following the procedure of paragraph 1 of Example 97, except'using t-butyloxycarbonyl norleucine and dicyclohexylcarbodiimide tointroduce the norleucyl residue in lieu of the aspara-ginyl residue.

EXAMPLE 131 Pyr-Asn-Trp-Pro-Lys-Pro The title compound is prepared following the procedure of Example 97, except using Net-b utyloxycarbonyl-N- trifluoroacetyl lysine for the introduction of the lysyl residue in place of N-t-buty1oxycarbonyl-N -dinitrophenyl histidine. The trifiuoroacetyl group is removed by treatment with piperidine at the end of the synthesis.

EXAMPLE 132 Pyr-Ser-Trp-Pro-Lys-Pro The title compound is prepared following the procedure of paragraph 1 of Example 98, except using N-t-*butyloxycarbonyl-N-trifluoroacetyl lysine for the introduction of the lysyl residue inplace of N-t-butyloxycarbonyl-N dinitrophenyl histidine. The trifluoroacetyl group is removed by treatment with piperidine at the end of the synthesis.

EXAMPLE 133 Pyr-Trp-Pro-Lys-Pro The title compound is prepared following the procedure of paragraph 1 of Example 30, except using N-t-butyloxycarbonyl-N -trifluoroacetyl lysine for the introduction of the lysyl residue in place of t-butyloxycarbonyl nitroarginine. The trifluoroacetyl group is removed by treatment with piperidine at the end of the synthesis.

EXAMPLE 134 Pyr-Asn-Trp-Pro-Gly-Pro The title compound is prepared following the procedure of paragraph 1 of Example 97, except using t-butyloxycarbonyl glycine in lieu of N -t-butyloxycarbonyl-N dinitrophenyl histidine.

EXAMPLE 1 3 5 iPyr-Nle-Trp-Pro-Gly-Pro The title compound is prepared following the procedure of paragraph 1 of Example 100, except using t-butyloxycarbonyl glycine in place of N-t-butyloxycarbonyl-N trifluoroacetyl lysine.

3 3 ester to introduce the asparaginyl residue in lieu of the glutaminyl residue.

2. Pyr -Trp -Pro-Arg-Pro-Asn-Ile-Pro-Pro.-The title compound is prepared by coupling the pentapeptide acid Pyr-Trp-Pro-Arg-P'ro (prepared as described in Example 30) to the tetrapeptide of paragraph 1 using the mixed carboxylic carbonic anhydride procedure.

EXAMPLE 138 Pyr-Trp-Pro-Arg-Pro-Asn-Ile-Pro-Pro 1. Pro-Asn-Ile-Pro-Pro.The title compound is prepared following the procedure of paragraph 1 of Example 81 except substituting t-butyloxycarbonyl asparagine pnitrophenyl ester to introduce the asparaginyl residue in lieu of the glutaminyl residue.

2. Arg-Pro-Asn-Ile-Pro-Pro.-The pentapeptide of paragraph 1 is coupled with t-butyloxycarbonyl nitroarginine 2,4-dinitrophenyl ester using the procedure of paragraph 7 of Example 1 but eliminating the washing with ammonia. The protected hexapeptide is subjected to hydrogenolysis to yield the title compound.

3. Pyr Trp Pro Arg Pro Asn Ile Pro Pro. The hexapeptide of paragraph 2 is coupled to the tripeptide Pyr-Trp-Pro following the procedure of paragraph 9 of Example 1 to yield the title compound.

EXAMPLE 139 Pyr-Trp-Pro-I-Iis-Pro-Asn-Ile-Pro-Pro 1. His-Pro-Asn-Ile-Pro-Pro.The title compound is prepared by coupling N-t-butyloxycarbonyl-N -dinitrophenyl histidine to the pentapeptide prepared as described in paragraph 1 of Example 138.

2. Pyr Trp Pro His Pro Asn Ile Pro Pro. The hexapeptide of paragraph 1 is coupled to the tripeptide Pyr-Trp-Pro following the procedure of paragraph 9 of Example 1 to yield the title compound.

EXAMPLE 140 Pyr-Trp-Pro-Lys-Pro-Asn-Ile-Pro-Pro EXAMPLE 141 Pyr-Trp-Pro-Gly-Pro-Asn-Ile-Pro-Pro l. Gly-Pro-Asn-Ile-Pro-Pro.The title compound is prepared following the procedure of paragraph 1 of Example 139 but substituting t-butyloxycarbonyl glycine for N -t-butyloxycarbonyl-N -dinitrophenyl histidine.

2. Pyr Trp Pro Gly Pro Asn Ile Pro Pro.-- The hexapeptide of paragraph 1 is coupled to the tripeptide Pyr-Trp-Pro following the procedure of paragraph 9 of Example 1 to yield the title compound.

EXAMPLE 142 Pyr-TrpaPro-His-Pro-Gln-Ile-Pro-Pro 1. His-Pro-Gln-Ile-Pro-Pro.-The title compound is prepared following the procedure of paragraph 2 of Example 81, but substituting N t-butyloxycarbonyl-N dinltrophenyl histidine for t-butyloxycarbonyl nitroarginine.

2. Pyr-Trp-Pro His-Pro-GlnJle-Pro-Pro. The hexapeptide of paragraph 1 is coupled to the tripept-ide Pyr- Trp-Pro following the procedure of paragraph 9 of Example 1 to yield the title compound.

34 EXAMPLE 143 Pyr-Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro 1. Gly-Pro-Gln-Ile-Pro-Pro. The title compound is prepared following the procedure of paragraph 2 of Example 81, but substituting t-butyloxycarbonyl glycine for t-butyloxycarbonyl nitroarginine.

2. Pyr-Trp-ProGly-Pro-Gln-Ile-Pro Pro. The hexapeptide of paragraph 1 is coupled to the tripeptide Pyr- Trp-Pro following the procedure of paragraph 9 of Example 1 to yield the title compound.

EXAMPLE 144 Cbc-TrpaPro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 3, except substituting cyclobutane carboxylic acid hydroxysuccinimido ester for cyclopent-ane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 145 Cbc-Tyr-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 6, except substituting cyclobutane carboxylic acid hydroxysuccinimido ester for cyclopentanc carboxylic acid hydroxysuccinimido ester.

EXAMPLE 146 'll3zl Cb c-Tyr-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 5, except substituting cyclobutane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 147 Cbc-Phe-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 2, except substituting cyclobutane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 148 Cbc-Gly Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 76, except substituting cyclobutane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 149 'Cbc-Leu-Pro-Arg Pro-'Gln-Ile-Pro-Pro The title compound .is prepared following the procedure of Example 78, except substituting cyclobutane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 150 Cbc-D-Trp-Pro-Arg Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 80, except substituting cyclobutane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 15 1 C-hc-Trp-Pro-Arg-Pro Gln-lle-Pro-Pro The title compound is prepared following the procedure of Example 3, except substituting cyclohexane carboxylic 35 z 3 acid hydroxysuccinimido-esterforcyclop ylic EXAMPLE'161 l r e eu z q e t fiHphe A1a Pro EXAMPLE 152 The title compound is prepared following the pro- .c p p g q cedure described in Example 54 except utilizing tert.-

The title compound is'preparedifollowing the I of Example 6, except substitutingcyclohexane carboxylic acid hydroxysuccinimido ester for cyclopentarie carboxylic acid hydroxysuccinimido ester.

EXAMPLE 153 Bzl' I Chc-Ty-r-Pro-Arg-Pro-'Gln-Ile Pro-Pro The title compound is prepared following the procedure of Example 5, except substituting cyclohexane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 1 5 4 Che-Phe-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 2, except substituting cyclohexane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 1 55 Chc-Gly-Pro-Arg-Pro-Gln-Ile-Pro-Pro The title compound is prepared following the procedure of Example 76, except substituting cyclohexane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 156 Chc-Leu-Pro-Arg-Pro-Gln-Ile Pro-Pro The title compound is prepared following the procedure of Example 78, except substituting cyclohexane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 157 Chc-D-Trp-Pro-Arg-Pro-Gln-Ile=Pro-Pro The title compound is prepared following the procedure of Example 80, except substituting cyclohcxane carboxylic acid hydroxysuccinimido ester for cyclopentane carboxylic acid hydroxysuccinimido ester.

EXAMPLE 1 5 8 Cbc-Trp-pro-Gly-Pro-Lys-BHphe-AlwPro The title compound is prepared following the procedure described in Example 54, except utilizing cyclobutane carboxylic acid hydroxysuccinimido ester in place of Cpc.

-' EXAMPLE 159' The title compound is prepared followingthe procedure described in Example 158=except utilizing tart.- butyloxycarbonyl norleucine and 'dic'yclohexylcarbodiimide in place of N-tert.-butyloxycarbonyl-N -benzyloxycarbonyl-lysine-p-nitrophenyl ester.

butyloxycarbonyl norleucine and dicyclohexylcarbodiimide in place of N-tert.-butyloxycarbonyl-N -benzy1- oxycarbonyl-lysine-p-nitrophenyl ester.

EXAMPLE 162 Chic-Trp-Pro-Gly-Pro-Nle-;3Hphe-Ala-Pro The title compound is prepared following the procedure described in Example 159 except utilizing tert.- butyloxycarbonyl norleucine and dicyclohexylcarbodiimide in place of N -tert.-butyloxycarbonyl N -benzyloxycarbonyl-lysine-p-nitrophenyl ester.

EXAMPLE 163 Pyr-Trp-Pro-Arg-Pro-Glu-Phe-Pro-Pro The title compound is prepared following the procedure described in Example 61, but substituting 'y-benzyl tert.-butyloxycarbonyl glutamic acid in place of tert.- butyloxycarbonyl glutamine.

EXAMPLE 164 For determination of I values (concentration of peptide expressed in micrograms/ml. producing a 50% inhition of angiotensin-converting enzyme), varying concentrations of peptide are added to 13 100 mm. assay tubes containing a final volume of 0.25 ml. containing mM. potassium phosphate buffer, pH 7.5, 30 mM. NaCl, and 0.3 mM. angiotensin I. Enzymatic reactions are initiated by addiiton of enzyme and incubation is carried out at 37. The concentration of representative peptides of the present invention which inhibit conversion of 50% of angiotensin I into angiotensin I I is shown in the following table:

Peptide of Example I g/ml.)

EXAMPLE Representative peptides of the present invention are administered intravenously to anesthetized male rats of the Sprague-Dawley strain weighing from 250 to 450 g. followed by an injection of 0.10 g/kg. of angiotensin I.

The following table indicates the peptide administered as well as the degree of inhibition relative to administration of angiotensin I above.

37 p e 38 7 Maximum wherein N is cyclobutylcarboxylic acid, cyclopentylinhibition of carboxylic acid or cyclohexylcarboxylic acid and O angiotensin I B 1 induced pressor Dose Number (p r r a f lus T T '1 Ph G1 Le D T Peptide of example (mg./kg.) animals standard e i'ror) 5 18 or 4 HA 5 N-Trp-Pro-Gly-Pro-Lys-pHphe-Ala-Pro 518 g 2? wherein N is as defined above and fiHphe is 3-amino- 2.0 4 41.5198 4-phenylbutyric acid; 312 i 23E332 10 (9) A nonapeptide of the formula :13 2 ia fi pGlu-Trp-Pro-P-Pro-Q-Ile-Pro-Pro 32.0 4 73313.0

0.5 3 55.7=|=13.a wherem P 18 Arg, H1s, Lys or Gly and Q 1s Gln or 2.0 4 37. 4=|=3.6 3-2 2 33%; 1 T P R S A1 210 4 3117314 IP' to -Pm- -T a'Pro wherein R is Arg or Orn, S is Nle or Gln and T is What is claimed is: Ile or Phe; 1. A peptide having one of the following formulas: ,o (1) An acylated tripeptlde of the formula 2 wherein S and T are as defined above; Cac-Phe-Ala-Pro pGlu-O-Pro-Arg-Pro-Gln-Ile-Pro-Pro wherein Cac 1s chloroacetic acld; (2) A tetrapeptide of the formula Wherem 0 15 as defined above;

PGluTrFAlwPm or pGlu-Trp-Pro-Arg-Pro-Nle-T-Pro-Pro (3) An acylated tetrapeptide of the formula wherein T is as defined above;

Dac-Gly-Phe-Ala-Pro or A-Lys-Phe-Ala-Pro P P' wherein Dac is diazoacetic acid and A is chloroacetic PGIu'TTPPro'AIg'PmLYS'Phe'AIa'Pm acid, cyclobutylcarboxylic acid, cyclopentylcarboxylic 3O G1 -p -p 1 11 ac1d or cyclohexylcarboxylic acid, P p

(4) A pentapeptide of the formula pGlu-B-Phe-Ala-Pro wherein B is Lys, Nle, Glu or Gln;

pGlu-C-Trp-Ala-Pro wherein C is Nle, His, Orn or Arg; N pGlu-Lys-Trp-Ala-Pro; pGlu-Lys-E-Ala-Pro 40 wherein E is His; Ile, Pro, Ser or 3-amino-4-phenylpGlu-Trp-Pro-Gly-Pro-G1u-Ile-Pro-Pro; pGlu-Lys-Phe-Ala-Pro-Gln-Ile-Pro-Pro;

(10) A decapeptide of the formula pGlu-K-Trp-Pro-P-Pro-Q-Ile-Pro-Pro wherein K, 'P and Q are as defined above;

pGlu-U-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro butyric acid; wherein U is Lys or Glu;

(11) An undecapeptide of the formula wherem F 5 Pro or Lac; pGlu-Trp-Pro-Arg-Pro-V-Pro-W-Ile-Pro-Pro PGm'Lys'Phe'Ala'G wherein V is Thr or Gly and W is Gln or Glu; or where! G 15 ASP or Glu; (12) A tridecapeptide of the formula PGIH'LYS'TIP'H p-Glu-Gly-Gly-Trp-Pro-Arg-Pro-Gly-Pro-W-Ile-Pro-Pro Wherem H 15 Ala'Gly or Ala'sar; wherein W is as defined above wherein unless otherpGlu-Trp-Pro-J-Pro wise indicated each optically active amino acid has the L-configuration. wherem I H1s, Lys or G 2. A peptide having one of the following formulas: (5) an acylated pentapeptlde of the formula X G1y Phe A1a Pm, Gly Phe Ala Pm.Tfa,

Dac-Gly-Gly-Phe-Ala-Pro X wherein Dac is diazoacetie acid; t A (6) A hexapeptide of the formula Y ys Phe 1a l pGlu-Lys-Phe-Ala-Pro-Pro, pGlu-K-Trp-Pro-Arg-Pro X LyS Phe A1a Pr, P

wherein K is Asn, Nle or Ser; w

pGlu-Nle-Trp-Pro-L-Pro N0 I wherem L 18 HIS or Gly; Pro-Q-Ile-Pro-Pro, pGlu-Trp-PrmArg-Pro;

pG1u ASn Trp Pro M Pr0 P-Pro-Q-IlePro-Pro, Thr-Pro-Gln-Ile-Pro-Pro, wherein M is Lys or Gly; f (7) An octapeptide of the formula T 1 11 p 1 pGlu-Ser-Trp-Pro-L-Pro, pGlu-Nle-Trp-Pro-Lys-Pro, (8) An acylated octapeptide of the formula 2 l N-O-Pro-Arg-Pro-Gln-Ile-Pro-Pro 5 pGlu-Ser-Trp-Pro-Arg-Pro,

39 Gly-Pro-Glu- Ile-Pro-l-ffro I Pro-V-Pro iln-Ile Pro-Pro,

i 7 z I pGlu-Trp-Pro-Arg Pro-Gly-Pro,

170 pGlu-Trp-Pro-Arg-Pro-Thr-Pro;

Arg-Pro-V-Pro-Gln-Ile-Pro-Pro,

Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro; Pro-Arg-ProV-Pro-Gln-Ile-Pro-Pro;

Trp-Pro-Arg-Pro-V-Pro-Gln-Ile-Pro-Pro,

wherein L is His or Gly, P is Arg, His, Lys or Gly, Q is Gln or Asn, V is Thr or Gly and W is Gln or Glu, and X and Y are amino protecting groups, provided X and Y are different when both are present in the same peptide wherein each optically active amino acid has the L-configuration.

3. A peptide having one of the following formulas:

Pro-Arg-Pro-Thr-Pro-Gln-Ile-Pro-Pro, Pro-Arg-Pro-Gly-Pro-Gln-Ile-Pro-Pro;

Trp-Pro-Arg-Pro-V-Pro-Gln-Ile-Pro-Pro, wherein Q is Gln or Asn and V is Thr or Gly. 4. An intermediate for the nonapeptide of the formula Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro having one of the following formulas:

Z-Ile-Pro-Pro-OBu Z-Gln-Ile-Pro-Pro-OBu Z-Pro-Gln-IIe-Pro-Pro-OBu 4 Z-Arg-Pro-Gln-Ile-Pro-Pro-OBu Arg-Pro-Gln-Ile-Pro-Pro-2HC1 pGIu-Trp-Pro-Arg-Pro or p v 170 I pGlu-Trp-Pro-Arg-Pro. 5. A compound of claim 1 having the name Cpc-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro wherein Cpc is cyclopentylcarboxylic acid.

6. A compound of claim 1 having the name Cpc-Phe-Pro-Arg-Pro-Gln-Ile Pro-Pro wherein Cpc is cyclopentylcarboxylic acid.

7. A compound of claim 1 having the name pGlu-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro. 8. A compound of claim 1 having the name pGlu-Trp-Pro-Lys-Pro-Gln-Ile-Pro-Pro.

9. A compound of claim 1 having the name pGlu-Trp-Pro-Gly-Pro-Gln-Ile-Pro-Pro.

10. A compound of claim 1 having the name pGlu-Trp-Pr0-Arg-Pro-Gln-Phe-Pro-Pro.

11. A compound of claim 1 having the name pGlu-Trp-Pro-Orn-Pro-Gln-Ile-Pro-Pro.

12. A compound of claim 1 having the name pGlu-Phe-Pro-Arg-Pro-Gln-Ile-Pro-Pro.

13. A compound of claim 1 having the name Bzl | pGlu-Tyr-Pro-Arg-Pro-Gln-Ile-Pro-Pro.

References Cited Lande, J. Org. Chem., 27, 4558-62 (1962).

Wunsch, Hoppe-Seylers Z. Phys. Chem., 322, 288-94 (1963).

LEWIS GOTTS, Primary Examiner R. J. SUYAT, Assistant Examiner US. Cl. X.R. 

1. AN ACYLATED TRIPEPTIDE OF THE FORMULA
 2. A TETRAPEPTIDE OF THE FORMULA
 3. AN ACYLATED TETRAPEPTIDE OF THE FORMULA
 4. A PENTAPEPTIDE OF THE FORMULA
 5. AN ACYLATED PENTAPEPTIDE OF THE FORMULA
 6. A HEXAPEPTIDE OF THE FORMULA
 7. AN OCTAPEPTIDE OF THE FORMULA
 8. AN ACYLATED OCTAPEPTIDE OF THE FORMULA
 9. A NONAPEPTIDE OF THE FORMULA
 10. A DECAPEPTIDE OF THE FORMULA
 11. AN UNDECAPEPTIDE OF THE FORMULA 